From Jacques More’ site, from an article on if God knows all future events:

King Saul
If you have read the previous chapter this is not totally new. This is an expansion and further explanation.
In Israel there was no king until God spoke to Samuel his prophet and directed him to pick out Saul a Benjamite to be their first king. Saul was chosen by God for this role, this post, as king (1 Samuel 10:24, 2 Samuel 21:6):

. . . Do you see him whom the LORD has chosen . . .

1 Samuel 10:24

. . . Saul, whom the LORD chose . . .

2 Samuel 21:6

After ruling for a while, Saul deliberately rebelled against God and on one such public occasion, Samuel came along and said these words to Saul:

You have done foolishly. You have not kept the commandment of the LORD your God, which He commanded you. For now the LORD would have established your kingdom over Israel forever. But now your kingdom shall not continue.
The LORD has sought for Himself a man after His own heart, and the LORD has commanded him to be commander over His people, because you have not kept what the LORD commanded you.

1 Samuel 13:13-14

I would like to look at ‘the LORD would have established your kingdom over Israel forever. But now your kingdom shall not continue’.

If the Bible is inspired and profitable for doctrine (2 Timothy 3:16) and God does not lie (Numbers 23:19, Titus 1:2), then I am bound to believe that God would indeed have established Saul’s kingdom over Israel for ever.

Now if God knew beforehand that Saul (the king He chose) was going to be a rebel like he became, then it is impossible for Him to have established his kingdom over Israel for ever.

So, either He would have established Saul’s kingdom, or, He would not. Since God does not lie, and I believe the above passage is scripture and therefore inspired by God, I can only conclude that God did not really know beforehand how Saul was going to end up.

For this passage to make full sense, the choice is simple, either God did not fully know beforehand and is telling the truth about the fact that He ‘would have established your [Saul’s] kingdom over Israel for ever’, or, God is not telling the truth: He in fact would not have established Saul’s kingdom, in the full advance knowledge that he was going to be rejected.

To my mind it is very plain: I believe God is telling the truth, the scripture is inspired and it makes full sense of God not to know fully the free choices of 1man

For full article, click here.