Being brought up to believe in a religion by parents/family as a young child, the same way they teach you to believe in Santa Claus, the Easter Bunny and the Tooth Fairy. The child is too naive to have personal opinions at such a young age and believes what they are told. This can wear off with age (like with Santa Claus, etc.) but usually sticks as religion is too controversial to be brought up as ‘not true’ in society.
No offense, but do you suffer from Santa Claus Syndrome?