Many Catholic doctrines are supported by the writings of the Gnostics and by the Apocrypha. The Apocrypha is a collection of books that are included in Catholic Bibles but excluded from Protestant Bibles.

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The Apocrypha is based on mysticism and supposedly contains secret doctrines. At the Catholic Council of Trent, this was decreed:

Whoever shall not receive as sacred and canonical all these books and every part of them, as they are commonly read in the Catholic Church, and are contained in the old Vulgate Latin edition, or shall knowingly and deliberately despise the aforesaid traditions, let him be accursed.ⁱ

The Apocryphal books were not considered part of Scripture by the Bible compilers, because they clearly contradict Biblical truths, as can be seen in the following examples:

Bewitching Art

The Apocrypha says this:

Open the fish, and take the heart and liver and the gall...if a devil or an evil spirit trouble any, we must make a smoke thereof before the man or the woman, and the party shall no more be vexed. As for the gall, it is good to anoint a man that hath witness in his eyes, and he shall be healed (Tobias 6:4-8).

But the Bible says this:

And signs will follow to those believing these things: in My name they will cast out demons (Mark 16:17).

But being distressed, and turning to the demonic spirit, Paul said, I command you in the name of Jesus Christ to come out of her! And it came out in that hour (Acts 16:18).

Salvation by Works

The Apocrypha says this:

For alms doth deliver from death, and shall purge away all sin (Tobias 12:9).

But the Bible says this:

Forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers (1 Peter 1:18-19).

Prayer for Dead

The Apocrypha says this:

For if he had not hoped that they that were slain should have risen again, it had been superfluous and vain to pray for the dead…Whereupon he made reconciliation for the dead, that they might be delivered from sin (2 Maccabees 12:43-46).

But the Bible says this:

But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin (1 John 1:7).

Errors in the Vulgate

The Bible translations that lean heavily on Catholic documents are highly problematic in some of their renditions. Some examples from the Vulgate Bible and translations based on the Vulgate pave the way for relic worship and question the level of God’s inspiration.

2 Timothy 3:16 KJV says, “All Scripture is given by inspiration of God.”
The Douay Version says, “All Scripture inspired of God is profitable.”

Hebrews 11:21 KJV says, “Jacob worshipped leaning upon the top of his staff.”
The Vulgate says, “Jacob adored the top of his rod.”

Revelation 22:14 KJV says, “Blessed are they that do his commandments.”
The Codex Vaticanus says, “Blessed are they that wash their robes.”

Read about other errors in doctrine that the Catholic Church has introduced

i. Council of Trent, fourth session.