Is it wrong to practice a belief which one does not believe or finds to be

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Is it wrong to practice a belief which one does not believe or finds to be irrational? For instance, are cultural Christians like Richard Dawkins intellectually irresponsible for adhering to practices connected with the belief which they find unconvincing? This is a very bugging question for me since I am a Christian who is becoming more and more disillusioned with my religious beliefs, so a philosophical answer would be very much appreciated. Thank you.