Exodus 31:18 And he gave unto Moses, when he had made an end of communing with him upon mount Sinai, two tables of testimony, tables of stone, written with the finger of God.
Exodus 32:16 And the tables were the work of God, and the writing was the writing of God, graven upon the tables.
Each context is different - but when God writes something (with His finger or His Spirit), it is something only He could do!
Statement made by Pharaoh's lost magicians - who could not copy God's miracles and plagues:
Exodus 8:19 Then the magicians said unto Pharaoh, This is the finger of God: and Pharaoh's heart was hardened, and he hearkened not unto them; as the LORD had said.
God writing about the judgment of Babylon, literally moments before it happened:
Daniel 5:5 In the same hour came forth fingers of a man's hand, and wrote over against the candlestick upon the plaister of the wall of the king's palace: and the king saw the part of the hand that wrote.
Sure the Devil can lie and make up his own false prophecies - but here we see God foretelling exactly what He was going to do, and nothing could stop Him or hinder Him from fulfilling His judgment on Babylon.
Jesus' power and authority to cast out devils:
Luke 11:20 But if I with the finger of God cast out devils, no doubt the kingdom of God is come upon you.
I find this passage really neat - it doesn't say what Jesus wrote - but here we see the finger of God writing again:
John 8:3-11 And the scribes and Pharisees brought unto him a woman taken in adultery; and when they had set her in the midst, They say unto him, Master, this woman was taken in adultery, in the very act. Now Moses in the law commanded us, that such should be stoned: but what sayest thou? This they said, tempting him, that they might have to accuse him. But Jesus stooped down, and with his finger wrote on the ground, as though he heard them not. So when they continued asking him, he lifted up himself, and said unto them, He that is without sin among you, let him first cast a stone at her. And again he stooped down, and wrote on the ground. And they which heard it, being convicted by their own conscience, went out one by one, beginning at the eldest, even unto the last: and Jesus was left alone, and the woman standing in the midst. When Jesus had lifted up himself, and saw none but the woman, he said unto her, Woman, where are those thine accusers? hath no man condemned thee? She said, No man, Lord. And Jesus said unto her, Neither do I condemn thee: go, and sin no more.
Notice in the above passage, it was the Word of God that Jesus spoke that convicted them of their sins, not what was written on the ground - but perhaps the writing recalled to mind the rest of the Law of Moses. To me, when I read that passage, it makes me think of mercy. Jesus wasn't writing to condemn, but to offer forgiveness and mercy. First, He had to confront them with their sin and the Law they had broken, then mercy was available to forgive.
My favourite, and one that is directly applicable to all believers today:
Jeremiah 31:33 But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people.
2 Corinthians 3:2-3 Ye are our epistle written in our hearts, known and read of all men: Forasmuch as ye are manifestly declared to be the epistle of Christ ministered by us, written not with ink, but with the Spirit of the living God; not in tables of stone, but in fleshy tables of the heart.
2 Corinthians 3:5-8 Not that we are sufficient of ourselves to think any thing as of ourselves; but our sufficiency is of God; Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life. But if the ministration of death, written and engraven in stones, was glorious, so that the children of Israel could not stedfastly behold the face of Moses for the glory of his countenance; which glory was to be done away: How shall not the ministration of the spirit be rather glorious?
The writing of the Holy Spirit of God upon our hearts is more glorious than the writing of the Law on stone tablets. Written in stone and written in our hearts.
2 Corinthians 3:18 But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, even as by the Spirit of the Lord.
As we gaze steadfastly into the Word of God, which the Holy Spirit inspired and moved holy men of God to pen down for us (see 2 Timothy 3:16 and 2 Peter 1:21), and behold the glory of the Lord Jesus Christ therein - in the volume of the book (Hebrews 10:7), from cover to cover - as we see Jesus in the pages of the Bible and let the Holy Spirit do His wondrous work in our hearts and lives, we are transformed into His image.
What is God writing in you?