Whether for the sake of curiosity or part of the debate on eternal security, many wonder if King Saul was saved. For the most part, the notion that a Christian lose their salvation is mostly a New Testament argument; but if an Old Testament saint can be found, then I'd be proven wrong and the doctrine of salvation maintained by works justified. Of course we first have to determine if he was saved; and if he was, whether or not he ever lost his salvation. Many won’t like the answer, but the answer is obvious: Saul was a saved man. This we’ll presently demonstrate. And in so doing, the answer to the second question will be, or should be, evident.
1 Sam. 10:6 And the Spirit of the LORD will come upon thee, and thou shalt prophesy with them, and shalt be turned into another man.
1 Sam. 10:9 And it was so, that when he had turned his back to go from Samuel, God gave him [Saul] another heart: and all those came to pass that day.
If these two verses don't refer to salvation, then what are they referring to? But there's more. In speaking to the witch at En Dor, Samuel told Saul that he and his sons would be with him the next day because King Saul and his sons were going to die in battle.
1 Sam. 28:19 Moreover the LORD will also deliver Israel with thee into the hand of the Philistines: and to morrow shalt thou and thy sons be with me: the LORD also shall deliver the host of Israel into the hand of the Philistines.
Now Samuel was a saved man, and he says here that when Saul and his sons die, that they’ll be with him. This is clearly teaching that Saul and his sons are going to Heaven. Furthermore, 1 Sam. 15:35 says:
And Samuel came no more to see Saul until the day of his death: nevertheless Samuel mourned for Saul: and the LORD repented that he had made Saul king over Israel.
Samuel is dead at the time of Saul's death, and yet he says that he’ll not see him until the day of his death. From 1 Sam. 28:19, we learn that this passage was both prophetic and that it teaches that Saul went to the same place as Samuel. Samuel saw Saul when he visited the witch at En Dor and in Heaven after he died. Saul went to see the medium in the night and later that same day he was slain. Thus, again, a true prophecy on two accounts: the correct prophecy that Saul would die later the same day along with the prophecy from 1 Sam. 15:35. Now since Samuel and Saul are in the same place, then it goes without saying that if Samuel wasn't saved, then neither was Saul. But Samuel was saved and so King Saul is with him.
But many suggest that since Saul was rejected by God that it meant that he lost his salvation (1 Sam. 15). Hogwash! King Saul was rejected as king and not as a “Christian.” It should also be noted that he wasn't removed from the throne right away. That didn't happen until some 15 years later and it happened by his own hand when he committed suicide on the battlefield (1 Sam. 31:4).
Saul did prophesy and there’s no indication that he ever spoke any false prophecies. This of course isn't proof-positive because false prophets can give true prophecies. The difference, of course, is in what direction they're pointing you – towards or away from God; and there’s no indication that Saul ever tried to teach a false gospel although it’s true that he had many personal failures – else he would have been stoned; and so the evidence in Scripture clearly supports that he was a Christian although he was backslidden or carnal, but not apostate.
But then there’s the case of the evil spirit that the Lord sent to trouble Saul. Some view this as a case of demon possession, but it’s only demon oppression. When David played his harp, Saul was comforted and the demon left. But noticeably lacking are the signs that often accompany demon possession such as being thrown to the ground (e.g. Mt. 17:14-18).
In summation, Scripture clearly teaches that Saul was a saved man. Granted, he wasn't much of an example (sounds like many Christians today, eh?). But Scripture makes it clear that he was saved. That, or else Samuel didn't make it either. So if King Saul, an Old Testament saint, can constantly rebel against God, seek to kill others, and commit suicide, and still make it to Heaven, then who are we to think that we're in any more danger of losing our salvation than they? Furthermore, they didn't have the indwelling Holy Spirit nor were they sealed by the Holy Spirit. We are. So are we to believe that we're more danger of losing our salvation than they? Such a thought is ludicrous. Samson was a womanizing Christian who also killed himself, but yet he’s regarded as a "hero of the faith" (Heb. 11:32). Again, if a Christian can lose their salvation, then what sins do they have to commit before they finally lose it? Selah.
 Great debate often ensues regarding this occasion. Conferring with familiar spirits is a sin punishable by death (Lev. 20:6, 27), but notice that the woman was shocked when Samuel appeared. Why? She was expecting her familiar spirit and not Samuel! Also note that Samuel gave godly counsel and a true prophecy; and since when is Satan interested in telling the truth (Jn. 8:44)? Also note that the prophecy involved Saul and his sons. Jonathan, one of Saul's sons, was a godly man – a man that entered into covenant with David and constantly sought to defend him from his father – even though he realized that he wouldn't be sitting on the throne (1 Sam. 23:16-17). We should therefore understand that this is a unique event that God allowed. If you reject this interpretation, then you must defend how Satan and his demons speak true prophecies. Satan appears as an angel of light; he isn't one (2 Cor. 11:14). Selah.
 1 Sam. 10:10-13; 19:19-24
 E.g. Caiaphas; Jn. 11:49-52; Mt. 7:21-23
 Dt. 13:1-5; 18:18-22
 1 Sam. 16:14-23; 18:10-11; 19:9-10