God sent an evil spirit? 1 Samuel 16:14

1 Samuel 16:14 Now the Spirit of the LORD had departed from Saul, and an evil spirit from the LORD tormented him.

1 Samuel 18:10 The next day an evil spirit from God came forcefully upon Saul. He was prophesying in his house, while David was playing the harp, as he usually did. Saul had a spear in his hand.

1 Samuel 19:9 But an evil spirit from the LORD came upon Saul as he was sitting in his house with his spear in his hand. While David was playing the harp.

First, the term "evil," does not always mean evil in the absolute moral sense, but rather, as in this case, something that is annoying and troubling.

Second, mankind, save Christ, is absolutely depraved - dead in trespasses and sin (Eph. 2:1). But for the grace of God, everyone has the capability of being an evil king such as Ahab or the next Hitler, etc. God in his mercy restrains much potential evil from ever fully and completely manifesting itself (Rom. 2:4; 3:26). We see this in Scripture in Genesis 11:1-9. To prevent a premature realization of a one-world kingdom under Nimrod, the Lord divided the people into nations, races, and languages. Additionally we see it in Job 2:1-6, where Satan is not allowed to kill Job, et. al. Judas and Saul seem to be two peas of the same pod, God lifting his restraints, and both exposing who they really were nearer the end of their lives.

God is absolutely sovereign. Nothing can happen without his permission. When God lifts his restraints things happen (1 Kings 22:22; Judg. 9:23) - like evil spirits causing distress in those that have rejected him (Why was Saul rejected by God? and God regretted setting up Saul to be king in Israel?).

In addition, God in his holiness judges sin - as he judged even in the days of Noah (Gen. 6 ff). God's judgment of sin comes in many forms. These forms do not make him unholy, but rather demonstrate his perfect holiness through divine judgment.

The Dictionary of Biblical Imagery has some interesting comments:

Demons as Political, Emotional and Psychological Problems.

Just as demons lay behind physical problems, evil spirits were also viewed as agents of emotional problems. Demons interfered in the international politics of Persia, Israel and Greece (Dan 10:13; 10:20; 12:1). Local political intrigue, such as the enmity between Abimelech and the rulers of Shechem, also indicated the work of an evil spirit from God (Judg 9:23). Behind the paranoid behavior of King Saul lurks an evil spirit from the LORD (1 Sam 16:1423; 18:10; 19:9). The errant oracle by the kings prophet is explained as the work of a lying spirit from among the host of heaven which stands before the Lord (1 Kings 22:22). Matthew's Gospel identifies jealousy with the description evil eye, familiar to all Mediterranean peoples as a demonic designation (Mt 20:15, cf. 6:23). The terminology applied to these evils shows that behind them the ancients saw demons, the personified agents of evil in a fallen world.

Ryken, L., Wilhoit, J., Longman, T., Duriez, C., Penney, D., & Reid, D. G. (2000). Dictionary of Biblical Imagery (electronic ed.) (203). Downers Grove, IL: InterVarsity Press.