What is a Heresy ? Simple words

What is a Heresy ? And how can I explain in simple way ? How many Heresy are there? Explain ?
Peace to all


Heresy is the obstinate post-baptismal denial of some truth of the Catholic faith.

Heresies are innumerable. Pick a Catholic truth, deny it, there’s your heresy.


thanks for answering

To clarify, the closer a matter being denied is to the Articles of Faith, as laid down in the major creeds, or in the Councils, the more likely it is “heresy” in the strict sense. Denying, for example, the two Natures of Christ, would be heretical in the strict sense. On the other hand, saying that contraception is moral would not be heretical in the strict sense, despite being an erroneous and immoral position to hold under other criteria. In other words, heresy deals with matters of faith as revelation, whereas lesser kinds of errors deal with other things which can be very important (like a lot of “life issues”) or less important (like specific positions on climate change/ecology).



They are countless but they all meet at one point, which Pope Saint Pius X defined as “the synthesis of all heresy” and to which he gave the name Modernism.

Modernism is the idea that the truth is not fixed and can be altered to suit the times.


Thanks for bringing up this distinction! There are a lot of people who disagree with the church on these “life issues” but who still deeply believe in God and that the church was true.

I remember how frustrating it was when I tried explaining this to someone awhile ago who insisted that stances on “life issues” were equal in importance to dogmas or even revelation.

@3335, you asked a very wide-ranging question. In the old online Catholic Encyclopedia you will find an appropriately wide-ranging answer.

Ok, Thanks for answering.

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A truth taken too far.

The devil cannot invent evil, he can only distort good to make evil. CS Lewis made a nice point of that in Screwtape letters. Many times at the core of a heresy is a truth, which I suppose, makes it all the more appealing.

Here is a copy/paste example, NO LIMIT on # of heresies

Ultimately, the doctrine of the Trinity—one in essence, three in Person—is “a word from another world,”
“All Christians believe the doctrine of the Trinity. If you do not believe this—that is, if you have come to a settled conclusion that the doctrine of the Trinity is not true—you are not a Christian at all. You are in fact a heretic. Those words may sound harsh, but they represent the judgment of the Christian Church across the centuries. What is the Trinity? Christians in every land unite in proclaiming that our God eternally exists as Father, Son, and Holy Spirit. Those who deny that truth place themselves outside the pale of Christian orthodoxy.”

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