This is true.
Firstly, when researching religious writings, look for the oldest known versions and compare any translations. Hebrew is difficult because the written language doesn't include vowels.
Secondly, compare translations as the writings progress through history. For instance the Tanakh to the Catholic and Orthodox Old Testaments, then to the King James Version and so forth to the NIV. Seeing what changes
are being made can give one an idea of the intent of those re-writing it.
I have noted that the older the original religion being plagiarized is, the better it was.
For instance, the bible is a plagiarism of Sumerian and Egyptian myths.
The Egyptian myth, especially, shows a much better overall ideology that the garbage religions that plagiarized the Egyptian myth.
Both of those traditions are close to what Gnostic Christianity is.
Christianity has taken the best out of them. That being the introspection and meditation that is to open our third or single eye.
The scribes removed almost all references to this but they did miss the odd text.
Here is the real way to salvation that Jesus taught.
Matthew 6:22 The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light.
John 14:23 Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.
Romans 8:29 For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.
Allan Watts explain those quotes in detail.