I've mentioned The Five Gospels on these pages before. It was compiled by a group of Biblical scholars from a wide variety of religious backgrounds - collectively known as The Jesus Seminar. They analyzed, argued over, and voted upon the authenticity of every saying attributed to Jesus in the four canonical gospels, plus "Thomas". Using the old "red-letter" Bibles as a framework, each saying was given weighted ratings and printed in a different color, accordingly:

Red: Jesus undoubtedly said this or something very like it.

Pink: Jesus probably said something like this.

Gray: Jesus did not say this, but the ideas contained in it are close to his own.

Black: Jesus did not say this; it represents the perspective or content of a later or different tradition.

It's surprising to find so few of the alleged words granted the red color: approximately 20% overall (but, for instance, almost none in the Gospel of John).

It's also instructive to see how much black there is. Putting words in Jesus' mouth to influence conflicts within the movement that became Christianity, and to attract more converts, seems to have begun almost immediately. Small wonder that anyone who claims to be "Christian" gets away with it.