Jason would try to make claim with all his false teachings that a person may be as son of God today and a son of the Devil tomorrow. He would say that even those who are born of the Spirit, justified and sanctified, may become reprobate and perish eternally. I believe it is because he does not understand the condition of a man from birth, and the condition of a man who is 'born again' because he himself has not yet been made new.
Regeneration is a radical and supernatural change of a man's inner nature, a realm in which man has no control over. This process through which the soul is made spiritually alive gives a man new character, a character built to be progressively be more like Christ. This process, because it was started by the only Power capable of doing so, is a sufficient guarantee that the new life given shall be permanent. No creature is at liberty to change it's own nature in an effort to become either a son of God, or the Devil.
The one who attempts to earn the smallest part of his salvation by works becomes "a debtor to do the whole law" perfectly. This is a different system of salvation, diametrically opposed to salvation by grace, a system of a religion that is not Christianity. Faith and repentance are gifts of God, and the bestowing of these gifts are the revelation of His purpose to save those to whom these gifts are given. No one can return these gifts, and no one can take them away. True Christians have within them the principle of eternal life, and that principle is the Holy Spirit. How can a Christian man's body, which is a "temple of the Holy Spirit", become the habitation of the Devil? Impossible, for this would be an insult to God!
So long as men remain in this world, they have remnants of the old sinful nature clinging to them. Our judgments may at times be wrong, as was that of the Galatians (Galatians 3:1); and our affections may cool, as in the Ephesian church (Revelation 2:4). "The church may become drowsy, yet her heart awakes" (Song 5:3). There is no possibility of anyone escaping the omnipotent power of God, so that like Jonah, who fled from the will of God eventually carried the message to Nineveh. If a man is truly saved, other than by an act of God Himself (which would mean He's gone back on His word), there is no possibility that he cannot fall away completely for His grace.
As Jason has clearly stated about us that we are careless and indifferent about our moral conduct and our growth in grace to be more like Christ. What he fails to realize is that the means as well as the end are both preordained by God. If it was foretold that a farmer would have a full field of delicious corn at the end of a harvest, then would all the means necessary for that to happen also be. The ideal Christian would commit no sin at all, however we understand that in our present place it is impossible. All those whom God has designed to render perfectly happy in eternity, He has designed to make in part happy in this world; and as holiness is essential to perfection, there is is a beginning of such perfection in our present place.
I feel bad for guys like Jason who can never be certain of his eternal salvation. He may indeed have the assurance of his present salvation, but he can not be certain of his inevitable salvation with its potential to be lost. According to his teachings his salvation might be highly probable, but there is no guarantee. I am thankful to God that my salvation does not rest upon the probability of my keeping it through fallible means. Since faith in Christ, which is a gift from God, is the means of salvation, and since this faith is not given to ALL men, the person who has it can be assured of their salvation.