You can't tell me the source of morals other than, "there could be another source..." - a pie in the sky zero evidence hope against hope leap of faith - and you call my assertion ridiculous!? Yeah right.
A hundred years ago, nobody could name a black hole. Did they exist a hundred years ago? Certainly. Not being able to name something doesn't mean it doesn't exist. Sheesh.
You have not one iota of evidence for a source of morality other than God - in fact, you are not even able to name a possibile source from your imagination! You can't even imagine it! Come on now, I can at least imagine a pink unicorn or the tooth fairy, but you can't even do that! Your argument cannot be more silly than it is.
Actually, I have named a possible source of morals. Incredibly, it is the same source as you assert -- the source of man.