I believe Catholic justification to be scriptural:
We are purified from sin according to scriptures.
1Jn 1:7 but if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.
2Pe 1:9 For whoever lacks these things is blind and shortsighted and has forgotten that he was cleansed from his old sins.
Our sins are taken away.
Joh 1:29 The next day he saw Jesus coming toward him, and said, "Behold, the Lamb of God, who takes away the sin of the world!
Heb 9:26 for then he would have had to suffer repeatedly since the foundation of the world. But as it is, he has appeared once for all at the end of the age to put away sin by the sacrifice of himself.
Heb 9:27 And just as it is appointed for men to die once, and after that comes judgment,
Heb 9:28 so Christ, having been offered once to bear the sins of many, will appear a second time, not to deal with sin but to save those who are eagerly waiting for him.
Our sins are cleared away.
Psa 50:3 Our God comes, he does not keep silence, before him is a devouring fire, round about him a mighty tempest.
Psa 102:12 But thou, O LORD, art enthroned for ever; thy name endures to all generations.
Isa 43:25 "I, I am He who blots out your transgressions for my own sake, and I will not remember your sins.
Justification is also a future process.
Rom 2:13 For it is not the hearers of the law who are righteous before God, but the doers of the law who will be justified.
Rom 3:20 For no human being will be justified in his sight by works of the law, since through the law comes knowledge of sin.
The scriptures belows tell us of Abraham’s justifications.
Heb 11:8 By faith Abraham obeyed when he was called to go out to a place which he was to receive as an inheritance; and he went out, not knowing where he was to go.
Gen 12:1 Now the LORD said to Abram, "Go from your country and your kindred and your father’s house to the land that I will show you.
Gen 12:2 And I will make of you a great nation, and I will bless you, and make your name great, so that you will be a blessing.
Gen 12:3 I will bless those who bless you, and him who curses you I will curse; and by you all the families of the earth shall bless themselves."
Gen 12:4 So Abram went, as the LORD had told him; and Lot went with him. Abram was seventy-five years old when he departed from Haran.
Rom 4:2 For if Abraham was justified by works, he has something to boast about, but not before God.
Rom 4:3 For what does the scripture say? “Abraham believed God, and it was reckoned to him as righteousness.”
Gen 15:6 And he believed the LORD; and he reckoned it to him as righteousness.
Jas 2:21 Was not Abraham our father justified by works, when he offered his son Isaac upon the altar?
Jas 2:22 You see that faith was active along with his works, and faith was completed by works,
Jas 2:23 and the scripture was fulfilled which says, “Abraham believed God, and it was reckoned to him as righteousness”; and he was called the friend of God.
Gen 22:1 After these things God tested Abraham, and said to him, “Abraham!” And he said, "Here am I."
Gen 22:2 He said, "Take your son, your only son Isaac, whom you love, and go to the land of Mori’ah, and offer him there as a burnt offering upon one of the mountains of which I shall tell you."
Gen 22:3 So Abraham rose early in the morning, saddled his ***, and took two of his young men with him, and his son Isaac; and he cut the wood for the burnt offering, and arose and went to the place of which God had told him.
Gen 22:4 On the third day Abraham lifted up his eyes and saw the place afar off.
Gen 22:5 Then Abraham said to his young men, "Stay here with the ***; I and the lad will go yonder and worship, and come again to you."
Gen 22:6 And Abraham took the wood of the burnt offering, and laid it on Isaac his son; and he took in his hand the fire and the knife. So they went both of them together.
Gen 22:7 And Isaac said to his father Abraham, “My father!” And he said, “Here am I, my son.” He said, "Behold, the fire and the wood; but where is the lamb for a burnt offering?"
Gen 22:8 Abraham said, “God will provide himself the lamb for a burnt offering, my son.” So they went both of them together.
Gen 22:9 When they came to the place of which God had told him, Abraham built an altar there, and laid the wood in order, and bound Isaac his son, and laid him on the altar, upon the wood.
Gen 22:10 Then Abraham put forth his hand, and took the knife to slay his son.
Gen 22:11 But the angel of the LORD called to him from heaven, and said, “Abraham, Abraham!” And he said, "Here am I."
Gen 22:12 He said, "Do not lay your hand on the lad or do anything to him; for now I know that you fear God, seeing you have not withheld your son, your only son, from me."
Gen 22:13 And Abraham lifted up his eyes and looked, and behold, behind him was a ram, caught in a thicket by his horns; and Abraham went and took the ram, and offered it up as a burnt offering instead of his son.
Gen 22:14 So Abraham called the name of that place The LORD will provide; as it is said to this day, "On the mount of the LORD it shall be provided."
Gen 22:15 And the angel of the LORD called to Abraham a second time from heaven,
Gen 22:16 and said, “By myself I have sworn, says the LORD, because you have done this, and have not withheld your son, your only son,
Gen 22:17 I will indeed bless you, and I will multiply your descendants as the stars of heaven and as the sand which is on the seashore. And your descendants shall possess the gate of their enemies,
Gen 22:18 and by your descendants shall all the nations of the earth bless themselves, because you have obeyed my voice.”
We must become partakers of the divine nature.
2Pe 1:4 by which he has granted to us his precious and very great promises, that through these you may escape from the corruption that is in the world because of passion, and become partakers of the divine nature.
Maybe it would be easier to approach the subject using the words of Protestants. Protestants are quick to ask, “are you saved”? We believe we are saved, we are being saved and we hope to be saved. In other words, we must work for our salvation.
Rom 8:24 For we are saved by hope. But hope that is seen is not hope. For what a man seeth, why doth he hope for?
Eph 2:5 Even when we were dead in sins, hath quickened us together in Christ (by whose grace you are saved)
Eph 2:8 For by grace you are saved through faith: and that not of yourselves, for it is the gift of God.
2Ti 1:9 Who hath delivered us and called us by his holy calling, not according to our own works, but according to his own purpose and grace, which was given us in Christ Jesus before the times of the world:
Titus 3:5 Not by the works of justice which we have done, but according to his mercy, he saved us, by the laver of regeneration and renovation of the Holy Ghost.
Php 2:12 Wherefore, my dearly beloved, (as you have always obeyed, not as in my presence only but much more now in my absence) with fear and trembling work out your salvation.
1Pe 1:9 Receiving the end of your faith, even the salvation of your souls.
Mat 10:22 And you shall be hated by all men for my name’s sake: but he that shall persevere unto the end, he shall be saved.
Mat 24:13 But he that shall persevere to the end, he shall be saved.
Mar 8:35 For whosoever will save his life shall lose it: and whosoever shall lose his life for my sake and the gospel shall save it.
Act 15:11 But by the grace of the Lord Jesus Christ, we believe to be saved, in like manner as they also.
Rom 5:9 Christ died for us. Much more therefore, being now justified by his blood, shall we be saved from wrath through him.
Rom 5:10 For if, when we were enemies, we were reconciled to God by the death of his Son: much more, being reconciled, shall we be saved by his life.
Rom 13:11 And that, knowing the season, that it is now the hour for us to rise from sleep. For now our salvation is nearer than when we believed.
1Co 3:15 If any mans work burn, he shall suffer loss: but he himself shall be saved, yet so as by fire.
1Co 5:5 To deliver such a one to Satan for the destruction of the flesh, that the spirit may be saved in the day of our Lord Jesus Christ.
Heb 9:28 So also Christ was offered once to exhaust the sins of many. The second time he shall appear without sin to them that expect him unto salvation.