Freud’s ideology was founded on his premise that God doesn’t exist. From this flawed premise proceeded all his ideas about religion.
Don’t make the mistake of thinking Freud was some brilliant thinker who was able to derive a particular wisdom about God’s existence.
Here’s the Freudian thought process on the matter:
1) I want to make my own rules (the product of Sigmund’s id)
2) If I convince myself God doesn’t exist, I can convince myself God’s moral law doesn’t exist (this occurs in Sigmund’s superego)
3) If God’s moral law doesn’t exist, I can construct my own morality (here Sigmund’s ego receives the integration of his id and his superego)
Meanwhile, Sigmund is lying to himself.
Actually, all atheists do this all the time. It's the entire flawed premise of "The God Delusion," "The End of Faith," and almost every argument any atheist has challenged me with. And sure enough, it goes back as far as Freud at least. It's a fascinating to see this appearing over and over again, from people who claim to be "free thinkers."