Things that begin to exist needs a Cause. God is Uncaused Cause.What created the creator? He/she didn't become something out of nothing.
God's power is from Himself. God is sufficient Cause to effect everything and keep it going. Greek and Roman Gods are inside creation. God is outside time space and matter.And who or what gave him/her such power? Why is your one god any more believable than the many Greek or Roman gods? The 20th century demonstrated what exactly?
Infinity exists as a concept. In time space and matter it does not exist. If we had an infinite number of days past we would never get to today.Is the universe infinite?
You don't know the difference between Santa Claus and God? Look when it comes to God this is where your head is.Simple minds can't rap themselves around incredible concepts like infinity. So they cling to mythical characters like Santa Claus to explain what they cannot understand.