What does miss Maudie mean by sometimes the bible in the hand of one man is worse than a whiskey bottle in the hand of - oh your father?

it is fairly straightforward. Their town is extremely religious and thus a priest would be the pinnacle of social standing, and as a result wields considerable influence. It is an insightful remark on the abuse of power, comparing religion due to its prominence and position in peoples lives, in the wrong hands as having infinitely worse consequences than an out of control drunkard due to the scope of potential damage towards society and individuals.

Cheers.