There's nothing our All-powerful God cannot do!
But is that a limit to omnipotence? No.
Consider this... If something is perfect it can't be not-perfect, but that doesn't limit its perfection; indeed, it magnifies it!
The same is true of God. He is perfect and all-powerful! He cannot taint His own goodness, but that is no limit to His power; indeed, it magnifies His power!
Sin is born out of moral weakness and a corrupt nature. The fact that God cannot sin is a testimony to His perfection and His power, that He is incapable of anything base or evil.
Our God is Holy! Absolutely perfect!
Let us worship Him as the perfect, all-powerful God He is!