1. Without virtue, civilization dies.
I think this is pretty self evident if we look at history. When virtue or a standard of conduct is taken out of society, 99.9% of the time the society fails.
2. Without religion, virtue dies.
Dostoyevsky said "If God doesn't exist, everything is permissible." So couldn't it also be said, as a corollary that because not everything is permissible, because we have a conscious that speaks with some authority, that God could exist?
Nietzsche, one of the greatest and most consistent atheists, agrees with the Dostoyevsky statement. His philosophy calls for a "superman" who will realize that "God is dead" and thus be freed from moral scruple and guilt. He sees morality as originating in the weakness of the herd and their resentment at this weakness; they invented morality to pull the teeth of the wolves so that they, the sheep, would not be devoured by them. Why should someone who believes this philosophy have moral scruples? Reason gives no real answer to this question, but history does. It wears a swastika.
Satre also agrees. From one of his works:
"God does not exist and we have to face all the consequences of this. The existentialist is strongly opposed to a certain kind of secular ethics which would like to abolish God with the least possible expense... The existentialist, on the contrary, thinks it very distressing that God does not exist, because all possibility of finding values in a heaven of ideas disappears along with Him..."
Along this line of thinking Voltaire also said, "If God does not exist, it becomes necessary to invent him." Also Charleston, "If I did not believe in God, I should still want my doctor, my lawyer, and my banker to do so."
3. Therefore, without religion, civilization dies.
They are corollary. If A=B and B=C, then A must equal C.
I personally am drawn most to the statement, that even if God doesn't exist, it's necessary to invent him.