logic is a machine. It accepts premises and cranks out conclusions. But where do the premises come from? On something physical and scientific, the premises are easy enough to come by. I dropped the ball, it fell to the ground. I dropped the peanut, it fell to the ground. I jumped and fell to the ground. Gravity. But when we get into the issue of religion, premises are much harder to come by: In fact, there is little objective basis to make a claim for or against the existence of a deity. Without a hard ground on which to found premises, the same, objective logic will crank out different conclusions.
"An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup." -H.L. Mencken