What's the difference between these two lines of reasoning? The logic of each is impeccable in its own way. But each is grounded in a different premise. The skeptical objection to the Gospel is premised in works-righteousness. But the logic of God is premised in grace: Christianity MUST be true, because only God would save sinners. God proves that He is God by His grace to sinners.
If you are in Christ, whatever God is doing in you life right now is not an experiment that He might abandon if He gets fed up with you. You need to know that God would have to stop being God before He'd quit on you. It's not because you risk looking like a failure. You already do. It is because God will never let His purpose fail. The defeat of grace to sinners would be the defeat of God.
The message of God to us all is this: 'For My Own sake, I love failures and fools and spiritual nitwits. My glory I will not give to another.'
God's commitment to God is His assurance to us."
~ Ray Ortlund, Jr.