Colbert is, of course, right on this one. The guest, perhaps unknowingly, is essentially trying to prove that God is not, in fact, God. If “God” was wrong, he is not God. Fortunately, Colbert knows enough theology to put this guy in his place in a way that will teach others the Truth in a way they will remember.
We do, indeed, send ourselves to Hell through abuse of our God-given free will. But He loves us enough to allow us to make that choice, rather than force us to love him, as He could. He could make us love him and want to spend eternity with Him, but that would involve denying our free choice to do so or not to do so. Love that is not freely given, but taken or forced, is not love, it’s rape. And that’s not the loving God we know we have.