James,
Solomon was definitely saved, though back-slided for a while.. He was definitely guilty of Idolatry and marrying of unbelievers but those are his only outward sins. Ecclesiastes is known as Solomons penitent words, noticed the ending,
"Remember now thy Creator in the days of thy youth, while the evil days come not, nor the years draw nigh, when thou shalt say, I have no pleasure in them;
Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.
For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil."
God choose Solomon, and Solomon was and is a man of God. Yes, he sinned and God judged him temporally for it which brought him back to God near the end but God through the shed blood of Christ forgave him spiritually and so his sins have been washed away.. So Yes Solomon I believe is in Heaven.. Salvation can not be lost, it has always been a free gift, By Grace in Christ through Faith Alone. Solomon was saved in the same way we are and did not lose his salvation, but did sin, and he repented which showed a true conversion..
Remember, God requires magistrates to BE men of God... God would not contradict himself, Notice Ex. 18 "Moreover thou shalt provide out of all the people able men, such as fear God, men of truth, hating covetousness; and place such over them, to be rulers of thousands, and rulers of hundreds, rulers of fifties, and rulers of tens"
This requires Magistrates to BE believers.. How much more when God chooses the man who will be king to be over the people... Solomon was also considered a Prophet which wrote scriptures and wrote prophetic utterances in the Psalms.. God would not have a Prophet that was chosen by God to be a Prophet and to be a spoke-voice of God and record Holy Words of God and Prophecy.. These were all gifts of a converted heart and one specially chosen by God....
Thats my two cents...
DuckyBill,
King Solomon was not a child of God sadly as that may sound. Here's a verse which helps us see that, despite of Solomon's wisdom that was given to him by God and the many beautiful verses that Solomon spoke about in Songs of Solomon.
1Ki 11:4 For it came to pass, when Solomon was old, that his wives turned away his heart after other gods: and his heart was not perfect with the LORD his God, as was the heart of David his father.
When know that King David was not entirely perfect in his ways all the days of his life but as you know with the language of David's heart being perfect before the Lord means that he was a child of God (as God the Holy Spirit gave King David a new spirit and a new heart after God's heart, sealed by the Holy Spirit)
King Solomon was not saved despite of building the Lord's House. He was just simply committing outward righteous acts at the very beginning when he built the Lord House and then his true nature begin to show when he started to mess with various women and setup altars for their Gods and never turned from his wicked ways. So he died as an unsaved person, meaning he died in his sins and did not died with Christ. I hope that helps.