I've studied the Moral Argument for God's Existence since the 1970s. I was doing my Bachelor's degree in philosophy. And, I was a new Christian. William Lane Craig was one of my campus pastors.
I have yet to meet an objection to this argument that dissuaded me from affirming the force of this argument.
Historically, the main objection to this argument is called the Euthyphro Dilemma, from Plato. In this video Bill again explains why and how this dilemma fails to debunk the Moral Argument.