Just for the record I do believe in God and that He is the source and standard for our behavior.
the conclusion will follow inescapably according to the rules of logic so long as one affirms premises (1) and (2) as true premises.
The Moral Argument Stated:
1) If God does not exist, objective moral values do not exist.
2) Objective moral values do exist.
It seems you must first be able to prove your first two points.
If I have a 5 Dollar Bill in my wallet, it will be objectively true that I have a 5 Dollar Bill in my wallet.
Your $5 bill is only worth what you can buy with it, which is dependent on where you spend it and whether or not you are able to talk the price of something down.
Not to mention that if you can convince an athiest of the existence of God, there is still the issue of which religion is correct and whether or not Jesus of Nazareth really existed and was raised from the dead after being crucified.