What is the evil spirit that God sent on Saul in 1 Samuel 19:1-10? Why would God send an evil spirit to Saul ?
This is a good question. At first glance, the scene depicted in 1 Samuel 19:1-10 does seem surprising, given what we know about God. It can seem to imply that God chose to afflict Saul with the evil spirit. However, if we look at the Hebrew and consider what we know from other passages in the Bible, it is consistent with what we know about God. The passage says (in the NIV), “But an evil spirit from the Lord came on Saul as he was sitting in his house with his spear in his hand.”
This passage does not say that God sent an evil spirit into Saul. It describes it as a spirit “from” the Lord. This could possible imply that God chose to make the evil spirit possess Saul. Alternatively, it could mean that a spirit which was created by God came on Saul, or it could mean that a spirit which the Lord gave permission to possess Saul came upon him. I believe that the interpretation which is consistent with other passages about God is the third one. In other words, the most reasonable interpretation is that God allowed this evil spirit to come on Saul.
A similar but not identical passage is found in the first chapter of Job. In this case, God allows Satan to tempt Job and to bring suffering into his life. In the end, nothing happens in the universe unless God allows it to happen. There are things which happen that God does not cause, but which he allows because he gives us, and presumably evil spirits free will. One could take Job 1 and say that when Satan afflicted Job he came “from” God, similar to what is stated in 1 Samuel 19:1-10.
God’s will is not always done. If it was, then Jesus would not have told us to pray “Your will be done” in the Lord’s prayer. God gives us freedom of will, and we often abuse that freedom to rebel against God and to do evil. In the broadest possible sense, even the evil that happens is allowed by God, even if it is not caused by God. I also believe that no one can be possessed by a demon who does not first live in a way which gives permission for that evil spirit to possess the person. I believe that this is exactly what happened to Saul. It also explains the wording of 1 Samuel 19:1-10.