This passage was a bit troubling upon first read. I came to 2 Samuel 1:14 that stated David killed the young Amalekite that brought news that he killed Saul (per Saul’s request) and David, who was grieved, killed him. I struggled to find many sources that have a good explanation. 

This site has a list of them, but I don’t find too many particularly helpful: http://biblehub.com/commentaries/2_samuel/1-15.htm

My thoughts on this are that the boy admitted treason by killing him. David did not always make the best “godly” decisions throughout his life. He also wanted to show publicly that he was grieved and not responsible for sending the boy to kill his king. The other possible reason is that Saul was appointed by God, and no one has authority to kill him except God. 

The boy was likely lying as pointed out by this site: https://hermeneutics.stackexchange.com/questions/1837/who-killed-saul so he was admitting treason on a lie hoping to gain favor. 

When I got to Samuel 28:12 I got to thinking about mediums and what they exactly were, etc and how she was able to have Saul communicate with Samuel. 

A medium is an intermediary between the physical world and the spiritual world. The link to this passage says:

“King Saul’s sinful use of a medium is recorded in 1 Samuel 28. The prophet Samuel was dead, and King Saul was frustrated that God had ceased telling him what to do through prophets or dreams. So the king, in direct violation of God’s Law and his own previous command, told his men to find a medium who could communicate with Samuel (1 Samuel 28:3). This medium conjured Samuel, and Saul communicated with the dead prophet. Theologians discuss whether this conjuring was a physical reappearance of Samuel or merely an image of him. There is also some question whether or not the medium actually meant to conjure Samuel, as she seems to have been the most surprised at his appearance—“When the woman saw Samuel, she cried out at the top of her voice” (verse 12). Perhaps she was a fraud who did not expect to actually see a spirit, or perhaps she was expecting to communicate with her “familiar” and not with Samuel directly. Either way, God seems to have allowed Samuel’s conjuring in order to drive home His point to Saul. The prophet’s message to Saul was one of doom (verses 17–19), and he died the next day. First Chronicles 10:13–14 reveals that Saul’s interaction with the medium was an important part of why he was dethroned and his dynasty cut short.”

The passage above is taken from https://www.gotquestions.org/what-is-a-medium.html – this has a lot more information. It also gives more information on why the Bible in both the New and Old Testament state this practice is a sin.)When researching through information for this post I also came across this book which I will be adding to my extensive reading list: https://www.christianbook.com/truth-behind-ghosts-mediums-psychic-phenomena/ron-rhodes/9780736919074/pd/19078?event=AFF&p=1011693&#CBD-PD-Description

MyPath2God.com recieves no money or referral fees from the link above. You can also buy it from Amazon (I just did to have it sent to my kindle.) I would rather give the Christian company my money, but being able to have all my book on one device is too much of a necessity.

I did not understand the verse: 
New International Version

“But an evil spirit from the LORD came on Saul as he was sitting in his house with his spear in his hand. While David was playing the lyre,” http://biblehub.com/1_samuel/19-9.htm

How or why would an evil spirit come from the Lord? 

This site https://markdriscoll.org/does-god-work-through-demons/ has three theories, a tormenting demon, a bad temperment, or a harmful spirit from God; all of which have some merit in explaining this verse. 

https://www.gotquestions.org/evil-spirit-Saul.html this site has some excellent explanations on the passage as well. Explaining instances where “God allowed Ananias and Sapphira to be filled with the spirit of Satan as a warning and example to the early church (Acts 5:1–11).”

When I got to the passage in Samuel 15:11 it said:

New International Version
“I regret that I have made Saul king, because he has turned away from me and has not carried out my instructions.” Samuel was angry, and he cried out to the LORD all that night. http://biblehub.com/1_samuel/15-11.htm

I was a bit confused, as I am sure many are… isn’t God omniscient? How could he regret doing anything? There is also the possibility that the way he created human “free will” and time, that he made it so that even he could not know exactly what a person would do? I’m sure if he chose to, he could, but maybe chooses not to? As humans, I am sure we are like children trying to understand advanced calculus here, but at each of these road blocks, I have to research and see what I can find. 

This website is from a podcast with a Pastor who answers questions: http://www.desiringgod.org/interviews/why-does-god-regret-and-repent-in-the-bible I did not unfortunately find this response super helpful, left me even more confused, but thought I would share since he makes some good points though. 

Another site I found that makes a similar point to the one above, but explains it in terms that I found easier to understand says “When God reflects on the disobedience of Saul, he uses a word that makes sense to us: the word “regret.” But this doesn’t mean God was ignorant about Saul’s sin or caught off guard by his rebellion. As John Piper points out, God is quite capable of lamenting a state of affairs he himself foreknew and brought about.” https://blogs.thegospelcoalition.org/kevindeyoung/2014/10/07/does-god-have-regret/  — I encourage you to read the whole passage, they make some excellent points.