When Jesus came into the world as the Messiah foretold in the ancient Scriptures, He demonstrated the reality of His claims in many ways. In Luke 11 we can read of a great victory over the powers of darkness by Him casting a devil out of one who had been robbed of the power of speech by the devil. However, when the Lord's enemies saw the remarkable miracle and heard the man speak in proof of his deliverance they accused Jesus of doing the miracle by the power of Beelzebub.
The Lord's answer was that the miracle was not the work of Satan but in fact had the fingerprint of God upon it. It was the kind of thing only God could do. And if their hearts had been honest they would have recognized both the miracle and the claims of the miracle worker. Jesus' ability to set this possessed man free from the power of the devil confirmed His claims of being the One who came to solve man's spiritual problem.
The works of God are unmistakable to the honest judge. His creation of the universe left a great testimony of omnipotence and wisdom. "The heavens declare the glory of God; and the firmament sheweth his handywork" (Psalm 19:1). Romans chapter one further assures us that our rational constitutions must lead us to a certain realization of God's existence and powers if we consider the Creation.
At times God intervenes in the course of human history so that we are constrained to confess that it can only be the providence of God. Even the magicians of Egypt came to a place where they were forced to recognize God's miracles and plagues He brought upon the country. "Then the magicians said unto Pharaoh, This is the finger of God" (Exodus 8:19a). What had happened was outside the sphere of natural explanation or imitation.
We can be very thankful that there is one Book that we can believe unreservedly because it also shows the unmistakable mark of God's hand. In fact the very first transcript of God's law is described as, "tables of stone, written with the finger of God" (Exodus 31:18b). The whole Bible is the very written Word of the Living God.