"It takes one to know one." I think this concept carries over to bias. When someone sees another person who is like her/him, affinity can form quicker or better. This then influences the thought process in relationship to this other person.

Christians have bias toward other christians who are like them. They gravitate toward each other and feed off each other. Sometimes they veered further from Christ because of that, because they find more comfort in the companionship of real people than from Christ's teachings.

I ought not be like that. I ought to gravitate toward Christ and Christ alone.

See
Same fork