As soon as you postulate the existence of an
independent metaphysical reality, such as the
Platonic world of
forms, or even the idea of
good and
evil, you will eventually have to resort to
God to back it up.
One or the other: If you believe in absolute truth, you're going to need God eventually. If you believe there is a set of truth somewhere out there that we are uncovering as we go, you're going to need God eventually. If you don't like this, re-evaluate your assumptions.
Yes, we made God up, but it doesn't mean he/she isn't real. We made war up too, and it's pretty freakin real. But we can also unmake God. (In our own image?)
Homer simpson: "God goes on, god goes off, god goes on, god goes off..."