This is the question I have pondered for years. I know that Jesus spoke well of Solomon, but we also know that he worshipped other God's, and fell from the faith later in life. However the doctrine of Perseverance of the faith is true I believe him to be in Heaven. If the Lordship teaching is 100% accurate he may be in Hell, but no doctrine is entirely Biblical and in the writings of Dr. Erwin Lutzer whom makes a case that some can fall in Homosexuality, fornication, among other sins, just end up in Heaven with fewer rewards may be a accurate case to describe Solomon. What say you? King Saul I believe may be an easier case whom is probably in Heaven, but I do not know for certain.