The Fear of the Lord pt 2

Why does the Spirit of the Lord leave Saul and an evil Spirit from God enter him (1 Sam 16:14; 18:10)?

Here its important to spiral out at the surrounding verses, starting with 1 Sam 18:10. First Saul chose to respond to David's fame by being "very angry" "galled" v8. Then Saul remained constantly jealous of David v9.  Saul cared about how David was perceived by others. The king was jealous of others.

In the second half of verse 10 Saul is "raving" (some translations say "prophesying") and Saul tries to spear David. This escalation of jealousy to attempted murder seems caused by the evil spirit indwelling.  *I fear God because I know I have been "jealous", "very angry" and by His grace has led me to the cross of Jesus and His blood rather than to Saul's spear.

Opening the scope larger as to why God sent an evil spirit, someone might be surprised that Saul was first anointed and commissioned by God (see chapters 9 and 10). Despite the God-approved anointing, Saul dishonored God, made unauthorized sacrifices (1 Sam 13:9). Here king Saul did not wait for the prophet Samuel, and showed he revere God and His sacrificial system only as it suited him. 

Spiraling outwardly more:  "Then the word of the Lord came to Samuel,  'I regret that I made Saul king, for he has turned away from following Me and has not carried out My instructions.'” (1 Sam 15: 10-11). I think God was provoked to send evil spirits to Saul because of Saul's actions -not just because He is God.  *I fear the Lord because He can change anyone for His plan regardless of merit, some have years of obedience and then God test with evil spirits.

On the outter spiral of this spirit-change is this truth:
"But today you (Israel) have rejected your God, who saves you from all your troubles and afflictions. You said to Him, ‘You must set a king over us.’" (1 Sam 10:19)
*I fear the Lord because all around me I live among a people who would rather have their gods and reject You and Your saving works. Yet, the Truth of Jesus Christ changed me. *I fear You Lord because You could send to me an evil spirit due to my nation that acts and speaks as if they don't need you. Instead I have a spirit that is hungry for You. Forgive us, Humble us and revive us.  

-God, Satan has the amount of power You permit him to have and not one ounce more. 
-Rid me Lord of jealousy, of living in fear of what others think.
-Rid me of spiritual impatience that would cause me to think I don't need the blood of Christ, like Saul did.