When we read heaven/hell (the traditional "hell" of Christendom) and saved/lost into every scripture, we end up missing quite a bit (and risk great loss). In our study on Walking in the Spirit we noted the Christian is quite capable of being rather slothful and wicked. Peter even goes as far as warning his readers (Jewish believers) they should not be condemned as murderers, thieves, evildoers or gossips.
But let none of you suffer as a murderer, a thief, an evildoer, or as a busybody in other people’s matters. -1 Peter 4:15
No, you yourselves do wrong and cheat, and you do these things to your brethren! Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God. And such were some of you. But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God. - 1 Cor 6:8-11
Therefore be imitators of God as dear children. And walk in love, as Christ also has loved us and given Himself for us, an offering and a sacrifice to God for a sweet-smelling aroma. But fornication and all uncleanness or covetousness, let it not even be named among you, as is fitting for saints; neither filthiness, nor foolish talking, nor coarse jesting, which are not fitting, but rather giving of thanks. For this you know, that no fornicator, unclean person, nor covetous man, who is an idolater, has any inheritance in the kingdom of Christ and God. -Eph 5:1-5
If all you have is heaven/hell and saved/lost what do you do with these? Paul is clearly addressing believers. He states they have been "washed." But if "the kingdom of God" must mean "heaven" because that is all you have, you're on perilous ground. Likewise, if we teach that "real Christians" can't be wicked, these warnings make no sense.
In looking through a number of commentaries on the passage in 1 Corinthians, I cannot seem to find a definitive statement of the loss of the kingdom in view save possibly in Daniel Whedon's commentary. As an Arminian he does not outright say that a Christian can forfeit the free gift of life through his name by faith (an Arminian belief)), but he sure muddies the water.
The central problem in all of these somewhat confusing commentaries is a misunderstanding of the many facets of God'd kingdom. As noted, Whedon was an Arminian. We expect him to deny the free gift. But what of the one who preaches the finished work of Christ and the free gift of life by faith alone? If we must have only saved/lost and heaven/hell what does not inheriting the kingdom entail?
Ironically, Whedon accidentally comes close to the truth when he writes:
This paragraph condemns... All idea that the being once justified insures, in spite of relapse into vice, a secured inheritance of God’s glorified kingdom...
Whedon is denying that "once justified" means "always justified" (for life, it does mean this), but had he understood the kingdom in view here, his statement would be true. One can have life and not inherit other promises. One can forfeit crowns, prizes, rewards. One can be "disqualified." We can be "vessels unto dishonor." None of that, however, is s forfeiture of the free gift of life by faith alone.
We saw in our studies on the parables that some servants will be cast out of the earthly kingdom. Some will forfeit blessings. Some will gnash teeth and weep. But these will see resurrection and have a promise of resurrection life. If we do not understand this, we end up denying the work of Christ and the free offer of life.
Once we understand the difference between that which is free and that which requires qualification (the just servant from the unjust servant are both servants), we can start to make sense of these passages (and many others).
If we fail to "mark the things which differ" (Phil 1:10), we may end up denying the cross or putting men under bondage to fear. Scripture is a tapestry which God wants us to study in way that we will be "approved." God wants us to seek out truth. The saved/lost and heaven/hell dichotomies melt scripture down to childish simplicities. We find ourselves explaining away difficult passages. Let us to the work of a workman and rightly divide God's word.