Man is what he believes.

Men are nearly always willing to believe what they wish

Demosthenes noted, “What a man wishes, he will believe.” And

Man is a credulous animal, and must believe something; in the absence of good grounds for belief, he will be satisfied with bad ones.

Man is what be believes.” — Anton Chekhov

The majority of men prefer delusion to truth. It soothes. It is easy to grasp. Above all, it fits more snugly than the truth into a universe of false appearances — of complex and irrational phenomena, defectively grasped.

The majority of men prefer delusion to truth. It soothes. It is easy to grasp.

I believe that people believe what they believe they believe.

It was his nature to believe anything, before he would believe he could be wrong.

One believes things because one has been conditioned to believe them.

A man is literally what he thinks.

Libenter homines id quod volunt credunt. (Roughly: It's easy for men to believe what they want to.)

A man lives by believing something; not by debating and arguing about many things.

the current situation being a toss-up as to what you want to believe. Man is not a rational animal, he is a rationalizing animal. Hence you will find that often what you believe is what you want to believe, rather than being the result of careful thinking.