Recently, I have heard a new doctrine proposed. It is that unfaithful Christians of this age will not be in the kingdom. That is, they will not participate in the millennial reign of Christ on earth, but will be excluded. Some actually teach that they will suffer in the lake of fire during this time because of their unfaithfulness. As it turns out, this is not a new doctrine at all. Appendix 5 in the book called Forgotten Truths is titled "Exclusion From Millennial Kingdom."

This appendix begins, "Exclusion from the millennial kingdom, we are told by some, will be the penalty imposed on Christians who lapse into immoral practices. And in proof of this we are referred to such passages as 1 Corinthians 6:9Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind,
See All..., 10; Galatians 5:21Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.
See All...; Ephesians 5:5For this ye know, that no whoremonger, nor unclean person, nor covetous man, who is an idolater, hath any inheritance in the kingdom of Christ and of God.
See All..., etc." He goes on to refute this false teaching on the basis that the kingdom of God as mentioned in the epistles of Paul is not a synonym for the millennial kingdom of Christ but refers to the spiritual kingdom of God (see Romans 14:17For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.
See All...; 1Corinthians 15:50Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
See All...).

The true believers in Christ have already been translated into the kingdom of His Son (Colossians 1:13Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son:
See All...). Rather than giving a way into the kingdom, the passages in question (1Corinthians 6:9Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind,
See All... and others) are exhorting us to walk worthy of the calling we have and not follow after the perversions of this world. 1Thessalonians 2:12That ye would walk worthy of God, who hath called you unto his kingdom and glory.
See All... states, "That ye would walk worthy of God, who hath called you unto his kingdom and glory." 2Thessalonians 1:5Which is a manifest token of the righteous judgment of God, that ye may be counted worthy of the kingdom of God, for which ye also suffer:
See All... states, "...that ye may be counted worthy of the kingdom of God, for which ye also suffer." As Sir Robert Anderson says, this is "a reference not to the future state, but to the place and calling of the Christian here and now. It is akin to the exhortations of Ephesians 4:1I therefore, the prisoner of the Lord, beseech you that ye walk worthy of the vocation wherewith ye are called,
See All...." This is where we are called upon to walk worthy of the vocation wherewith we are called.

So, when was this refutation of the doctrine of millennial exclusion written? It was initially published in the year 1914--that is, 90 years ago. There is nothing new under the sun.