The French mathematician Blaise Pascal (1623-62) put forward an argument that would appeal to agnostics. (An agnostic is someone who believes that it is impossible to prove God's existence.)
His argument goes something like this: God either exists or he does not. If we believe in God and he exists, we will be rewarded with eternal bliss in heaven. If we believe in God and he does not exist then at worst all we have forgone is a few sinful pleasures.
If we do not believe in God and he does exist we may enjoy a few sinful pleasures, but we may face eternal damnation. If we do not believe in God and he does not exist then our sins will not be punished.
Would any rational gambler think that the experience of a few sinful pleasures is worth the risk of eternal damnation?