1. Lack of evidence for god(s).
2. God being invoked as an explanation for everything, needs a much bigger explanation himself.
– The Problem of Hell.
– Why would the Abrahamic God, all-loving and all-powerful, allow natural evils to torment and kill people? Why can’t he keep kids from getting cancer? How did the Holocaust fit into God’s scheme?
– Why, if God wants us to know and accept him so much, does he hide himself from humanity?
– Why would an omnibenevolent God consign sinners to an eternity of horrible torment for crimes that don’t warrant that? (In fact, no crimes do!). The official Catholic doctrine, for instance, is that unconfessed homosexual acts doom you to an eternity of immolation in molten sulfur. And would the Christian God really let someone burn forever because they were Jews, or didn’t get baptized?
– Why is God in the Old Testament such a jerk, toying with people for his amusement, ordering genocides in which women and children are killed en masse, and allowing she-bears to kill a pack of kids just for making fun of a prophet’s baldness? How does that comport with the God worshipped today?
– Why didn’t Jesus return during his followers’ lifetime, as he promised?
– Why did God invent the devil?
– Might makes right: Why is something a sin when I do it, but not when God does it? E.g. I commit a sin if I kill someone, but God can kill everyone in the world apart from one family and that’s just fine and dandy.
– Why after seeing the 10 plagues and the parting of the Red Sea, 30-40% of the Hebrews decide they can make a better god themselves by melting some trinkets into the shape of a calf? Why just after receiving the commandment “thou shalt not kill” from God, Moses has them all murdered?
– If the Abrahamic God is the one, true, universal deity for all mankind, then why has he only ever concerned himself with the affairs of a bunch of Middle Eastern tribes living within a few hundred km radius of Jerusalem? Why did he totally ignore the rest of his supposed creation? Why no “prophets” for the Native Americans, Chinese, Australian Aborigines, Polynesians and many, many others?