"Where I heard that" is from the Christian Bible.
Consider Philippians, Chapter 3, Verse 2.
Philippians 3:2 in Other Translations
2 Watch out for those dogs, those people who do evil, those mutilators who say you must be circumcised to be saved.
Because not everyone knows this stuff: this is text from one of the Epistles (Latin for "letters") which are attributed to Paul of Tarsus also known as Saint Paul the Apostle. Apostle means one of the chief disciples of Jesus Christ. The Epistles provide instruction to early Christians on how to organize their churches.
@Archpawn@lemmy.world posts another relevant passage.
What made you disagree?