Is it a sin to convert to Islam?


The Church has also a high regard for the Muslims. They worship
God, who is one, living and subsistent, merciful and almighty, the
Creator of heaven and earth,[1] who has also spoken to men. They
strive to submit themselves without reserve to the bidden decrees of
God, just as Abraham submitted himself to God’s plan, to whose faith
Muslims eagerly link their own. Although not acknowledging him as God, they worship Jesus as a prophet, his virgin Mother they also honor, and even at times devoutly invoke. Further, they await the day of judgment and the reward of God following the resurrection of the dead.
For this reason they highly esteem an upright life and worship God, especially by way of prayer, alms-deeds and fasting.

If both Christians and Muslims do worship the same God … is it a sin to convert to Islam since your still worshiping the same God just in a different way :shrug:


I’m a Muslim. But from what I’ve been told the Catholic stance is that although Protestants, Jews and Muslims do worship the same God, they all have a flawed understanding of Him, and only the Catholic Church has the ‘fullness of truth’.


As a natural consequence of denying the triune nature of God, Muslims deny the divinity of Jesus and relegate Him to a mere prophet of lesser importance than Mohammed.

As far a I know, Muslims also claim that Jesus didn’t die on the cross and that someone took His place!


If you have once know Jesus as God. If you have believed that Jesus is God, the second Person of the Holy Trinity, and then deny that Jesus is God by your proclammation of faith as a Muslim, you are denying Him…
I think Jesus Himself answers this question best:

John 14**:11 ** Believe you not that I am in the Father, and the Father in me?

Matthew 10:33 But he that shall deny me before men, I will also deny him before my Father who is in heaven.

Luke 12**:9 **But he that shall deny me before men, shall be denied before the angels of God.

I would say that your soul is in mortal danger if you proceed on this path away from Jesus, the Christ.


I do not speak with any authority here, but I want to offer my opinion about this post.

Firstly, those passages you are quoting seem to be out of context. A Muslim doesn’t “deny” Jesus. They, however, do not believe Jesus to be God, like Catholics (and other Christians) do. But those verses you use don’t necessarily mean that Jesus was referring to anyone denying His divinity. Someone who doesnt believe Jesus is God can love Jesus more than one who is Trinitarian. Someone may not believe Jesus to be God, but they may not be able to see what you see and believe. They may think that they are following the right way.

Secondly, I don’t think someone would convert to Islam unless he believed it to be the true religion. No one who believes in the Catholic Faith would convert to Islam of his own free will.

I don’t think God would punish somebody for believing that he is following the truth.

Another thing is this: Someone who believes Jesus is God may deny Him before men. However, someone who believes that he is “only” a prophet may be martyred for believing in Jesus or His message.


Another thing is this: Someone who believes Jesus is God may deny Him before men. However, someone who believes that he is “only” a prophet may be martyred for believing in Jesus or His message.


In order for Christians to properly worship God, they really do need to follow Jesus (pbuh) in the most profound way possible i.e. by praying in the manner that he himself prayed.

In a book entitled, “To Pray as a Jew”, a lengthy explanation is given of the Prayers as done by the ancient Jews and a few of the contemporary Jews. In this book the author put diagrams showing the movement and positions during the prayer and one quickly realizes the similarity of the prayers of the Jews then and the Salat as practiced by the Muslims.

In his comment about these positions the author wrote : "In most contemporary congregations very few people keep to the tradition of falling prostrate. Sometimes it is only the Prayer leader and the rabbi who does so. In more traditional congregations, however, some worshipers, men and women, will join the Prayer Leader and rabbi in the act of prostrating themselves.

In Israeli synagogues, the practice is more widespread than in synagogues elsewhere. Since this is a position that we are unaccustomed to, one who has never done this before might very well demur. But once accomplished, the experience provides such a spiritual uplift that one looks forward to repeating it.

It is also interesting to learn from this book that the prayers of the Jews involve wash before the prayers, (like Wuduu or ablution for Muslims), and the call for Prayers (like the Azan for the Muslims).


Let’s try a different tack… not my words…


**I. JESUS **

452 The name Jesus means “God saves”. The child born of the Virgin Mary is called Jesus, “for he will save his people from their sins” (Mt 1:21): “there is no other name under heaven given among men by which we must be saved” (*Acts *4:12).
453 The title “Christ” means “Anointed One” (Messiah). Jesus is the Christ, for “God anointed Jesus of Nazareth with the Holy Spirit and with power” (Acts 10:38). He was the one “who is to come” (*Lk *7:19), the object of “the hope of Israel” (*Acts *28:20).
454 The title “Son of God” signifies the unique and eternal relationship of Jesus Christ to God his Father: he is the only Son of the Father (cf. *Jn *1:14, 18; 3:16, 18); he is God himself (cf. *Jn *1:1). To be a Christian, one must believe that Jesus Christ is the Son of God (cf. *Acts *8:37; *1 Jn *2:23).
455 The title “Lord” indicates divine sovereignty. To confess or invoke Jesus as Lord is to believe in his divinity. “No one can say ‘Jesus is Lord’ except by the Holy Spirit’” (*1 Cor *12:3).

18 Cf. Lk 1:31.
19 Mt 1:21; cf. 2:7.
20 Deut 5:6.
21 Cf. Ps 51:4,12.
22 Cf. Ps 79:9.
23 Cf. Jn 3:18; Acts 2:21; 5:41; 3 Jn 7; Rom 10:6-13.
24 Acts 4:12; cf. 9:14; Jas 2:7.
25 Cf.* Ex* 25:22; Lev 16:2,15-16; Num 7:89; Sir 50:20; Heb 9:5,7.
26 Rom 3:25; 2 Cor 5:19.
27 Phil 2:9-10; cf. Jn 12:28.
28 Cf. Acts 16:16-18; 19:13-16; Mk 16:17; Jn 15:16.
29 Cf.* Ex* 29:7; Lev 8:12; 1 Sam 9:16; 10:1; 16:1,12-13; 1 Kings 1:39; 19:16.
30 Cf. Ps 2:2; Acts 4:26-27.
31 Cf. Isa 11:2; 61:1; Zech 4:14; 6:13; Lk 4:16-21.
32 Lk 2:11.
33 Jn 10:36; cf. Lk 1:35.
34 Mt 1:20; cf. 1:16; Rom 1:1; 2 Tim 2:8; Rev 22:16.
35 St. Irenaeus, Adv. haeres. 3,18,3:PG 7/1,934.
36 Acts 10:38; Jn 1:31.
37 Mk 1:24; Jn 6:69; Acts 3:14.
38 Cf Mt 2:2; 9:27; 12:23; 15:22; 20:30; 21:9,15.
39 Cf. Jn 4:25-26; 6:15; 11:27; Mt 22:41-46; Lk 24:21.
40 Cf. Mt 16:16-23.
41 Jn 3:13; Mt 20:28; cf. Jn 6:62; Dan 7:13; Isa 53:10-12.
42 Cf. Jn 19:19-22; Lk 23:39-43.
43 Acts 2:36.
44 Cf. Deut 14:1; (LXX) 32:8; Job 1:6;* Ex* 4:22; Hos 2:1; 11:1; Jer 3:19; Sir 36:11; Wis 18:13; 2 Sam 7:14; Ps 82:6.
45 Cf. 1 Chr 17:13; Ps 2:7; Mt 27:54; Lk 23:47.
46 Mt 16:16-17.
47 Gal 1:15-16.
48 Acts 9:20.
49 Cf. 1 Thess 1:10; Jn 20:31; Mt 16:18.
50 Lk 22:70; cf. Mt 26:64; Mk 14:61-62.
51 Cf. Mt 11:27; 21:34-38; 24:36.
52 Mt 5:48; 6:8-9; 7:21; Lk 11:13; Jn 20:17.
53 Cf. Mt 3:17; cf. 17:5.
54 Jn 3:16; cf. 10:36.
55 Jn 3:18.
56 Mk 15:39.
57 Rom 1:3; cf. Acts 13:33.
58 Jn 1:14.
59 Cf.* Ex* 3:14.
60 Cf. 1 Cor 2:8.
61 Cf. Mt 22:41-46; cf. Acts 2:34-36; Heb 1:13; Jn 13:13.
62 Cf Mt 8:2; 14:30; 15:22; et al.
63 Cf. Lk 1:43; 2:11.
64 Jn 20:28,21:7.
65 Cf. Acts 2:34-36; Rom 9:5; Titus 2:13; Rev 5:13; Phil 2:6.
66 Cf. Rom 10:9; 1 Cor 12:3; Phil 2:9-11.
67 Cf. Rev 11:15; Mk 12:17; Acts 5:29.
68 GS 10 § 3; Cf. 45 § 2.
69 1 Cor 16:22; Rev 22:20.

I would also suggest you read, slowly and very carefully, John 6.


UG…I believe your conversion to Islam would be a horrible mistake. The christian faith has been around for 2,000 years, and life has overcome death through the One called Jesus Christ. Although muslims recognize Jesus, they do so only as a prophet, not as the Son of the Living God.

Matthew 10:33 But he that shall deny me before men, I will also deny him before my Father who is in heaven

You risk so much with your conversion to Islam, but the choice is yours to make.


It depends on how you define sin. If you define sin by the teachings of the Catholic church, then yes, it is a sin to convert to any other religion away from catholicism. This is the sin of apostasy, and falls under the 1st Commandment.

If you were baptized as a Catholic, then you are bound by the teachings of the church on sin, and therefore you can not convert under pain of sin. If one is not baptized as a Catholic, I can’t advise since I don’t know what other faiths teach on such a thing as apostasy. I believe the Qu’ran teaches you should be beheaded, but I can’t provide the text to prove that.

Edited to add a link on what the Qu’ran teaches on apostasy.


Of course it is a sin to convert to Islam. Whether or not it is a mortal sin depends on the circumstances: it is definitely grave matter. To convert from Catholicism to Islam is grave matter. Done with the ability to know and investigate the truths of the Catholic faith means that one has sufficient knowledge. And it is always a part of mortal sin to consent to committing apostasy. (Some acts are always mortal sin: apostasy, sacrilege, blasphemy, abortion, any crime against the sixth commandment, and to consent to them is always wrong. The only thing to save someone is that they are honestly mistaken about the nature of the act).

There are of course exceptions: a child, baptized by his parents, suffers the loss of his or her parents, say in a car accident. He or she ends up in an orphanage. A Muslim couple decides to adopt him, and raises him as a good Muslim. The child would have rejected Jesus Christ, however, he is not responsible.

But for an adult with full faculties were to convert to Islam, hence becoming an apostate, and has the ability and a reason to seek out the truth on religion, would lose his soul, for worshipping God in a way that is not approved by Him, and which is only found in the Roman Catholic Faith.

“For God so loved the world, as to give his only begotten Son; that whosoever believeth in Him, may not perish, but may have life everlasting. For God sent not His Son into the world, to judge the world, but that the world may be saved by Him. He that believeth in him is not judged. But he that doth not believe, is already judged: because he believeth not in the Name of the only begotten Son of God.” (John 3: 16-18).

Jesus saith to him: I am the way, and the truth, and the life. No man cometh to the Father, but by Me. (John 14: 6)

God bless,

Peter Rowe
Tiber class of 99/00


But you are denying that Jesus is the Son of God. So yes, objectively it is a grave sin.

Of course, presumably if someone converts to Islam they are doing so out of sincere conviction, and we can’t judge their heart. But converting to Islam out of social pressure or even out of fear for one’s life would be a grave sin.



Muslims and Christians do not worship the same God. It is a fact. Only Muslims want you to bellieve that we (Christian and Muslims) worship the same God. Muslims believe that Jesus is not God, so how can they say we worship the same God?

Just read John 1:1-14 and it will explain who Jesus really is. Then you will understand why Muslims don’t worship the same God as we do. Jesus is God and thats why muslims hate Christians.


just to clarify … I am NOT going to nor am I thinking of converting to Islam

This is just a question that crossed my mind when reading about the Catholic position on Islam. Bluntly it doesn’t make sense to me. The church declares that muslims worship the same God as christians when very obviously they don’t … but assuming they do worship the same God, if one converts from christianity to islam how is that person commiting apostacy if in essence their converting to the same God???
This didn’t make sense to me so I though I would ask

Thanks for your replies :slight_smile:


It is a sin to convert to Islam from Catholicism. Why? It is the sin against the 1st Commandment. You deny essentially all Christian doctrine concerning the Messiah, thus making conversion to Islam is a sin. Islam also deny the divinity of Jesus Christ. To deny this is a grave sin.

While we do worship the same God, Islam is not complete. It’s doctrine is partly true. They acknowledge One God, which is a true statement. In their belief, they deny that Jesus died on the cross.

The only perfect religion is Christianity which is founded in the Catholic Church.


They worship the same God-- the God of Abraham, Isaac, and Jacob.

They have an incomplete and incorrect understanding of the one, true God but they acknowledge the one, true God. This is true for the Jewish people as well.

This would not be true for Hindus, Buddhists, etc, as they do not have faith in the one, true God.

One would not be “converting to the same God” if one converted to Islam. Although such a person would acknowledge the one, true God, they would deny Christ’s divinity-- and if one knowingly does so after baptism into the Christian faith then one commits apostacy.

“Apostasy is the total repudiation of the Christian faith.” CCC 2089.


Consider a poor man who stole a loaf of bread from a rich man; Is that a sin? I hope not.

Consider a rich man who stole a loaf of bread from a poor man; Is that a sin? I hope so.

I reject the question in the original post because it does not take into consideration the person, their heart and mind, and their situations.


Please show me where scripture or Tradition has ever stated it is not a sin to steal if you are poor?


My God doesn’t allow for people to murder wholesale…to slaughter innocent women, children…to cut peoples heads off with dull knives, etc…They may claim Abraham as their father, as do the Jews…they are both Semitic…however, in my opinion, they don’t worship the same God as I do…and as far as I know the Church has not made this binding on my conscience. I know they say…“it is the radical Muslims doing all the killing”…well, that maybe be true…but until I see an outcry from the supposed “good Muslims” and a demand for the killing to stop,then I will continue to hold the same opinion of the religion…which due to Christian Charity I can not mention on a public forum. Remember…to all you supposed “good Muslims” out there…“Apathy is the glove into which evil slips its ugly hand”.


For the life of me…I am trying to understand the relevance…under what circumstances, would it be acceptable for a Catholic to convert to Islam??? None…even facing potential death. I believe enough in my Catholic faith to die for it…I can not imagine, nor would I consider, converting to anything else, be it Islam, Mormon, or even on of the 33,000 Protestant sects.

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit