First Corinthians 9: 25, 27
Kenneth S. Wuest Translation
25 But as for us [ we engage in Christian service, exercising constant self-control to obtain] a victor's garland which is imperishable. 27...lest somehow, when I have preached to others, I myself should be disqualified [ from further Christian service].
DISQUALIFY (Greek Definition) ADOKIMOS 96; unapproved, unworthy, from the neg. a, and DOKIMOS 1384, acceptable. Spurious, worthless. In a pass. sense, disapproved, rejected, cast away.
The context of 1 Corinthians 9:27 does not talk about salvation but about rewards. Salvation is positional, meaning it never changes. It does not depend on what we do because it is a gift. Ephesians 2:8,"...by grace you are saved" (positional) Reward, on the other hand, is conditional, so it depends on the performance of what God wills for us to do. Ephesians 2:9,"...for we are His handy work, created in Christ Jesus with a view to good works which God prepared beforehand in order that within their sphere we may order our behavior" (conditional).
1 Cor. 3:12-15, "He shall receive a reward. Assuming that the work of anyone, will be burned up, he will incur a loss, but he himself shall be saved, but being saved thus, it will be as escaping destruction in the midst of the fire which burns up his works."
There is no guarantee for a Christian of his rewards unless we follow the rule. The meaning of the word "reward" in the New Covenant is conditional. This means it is up to the believer to put himself under the guidance of the Holy Spirit in the obedience of the scriptures in his life, and to receive the rewards at the judgment seat of Christ. "...the things which were practiced to the agency of our body, whether they were good or bad," 2 Corinthians 5:10.
Let me first differentiate the Judgment Seat of Christ and the Great White Throne which are two different places. The Judgment Seat of Christ (2 Corinthians 5:10) is for all believers for their deeds: either rewards for services well done or losing rewards for the opposite. On the other hand, the Great White Throne (Revelations 20:11) is for all the world of sinners, the unbelievers, for the degree of sentence of the eternal imprisonment on the lake of fire.
What Paul had in mind here (going back to 1 Corinthians 3) for himself is to keep himself pure and separated, because he wants to do as much as possible being in his body in view of the judgment seat of Christ knowing that that will determine his position in heaven. It is not to receive salvation, but it is to shine for the glory of Christ in heaven. "I may finish my race (like a Greek athlete)," Acts 20:22-24.
1 Corinthians 3:10-11 : builders; teachers' responsibility
1 Corinthians 9:19 : preachers; winning soul
1 Timothy 4:16 : elders; preserving the assembly against false teaching
When the person is saved, he is saved forever (Ephesians 2:8)!
To all the Christians, keep yourself pure and separated from this evil world, and the Lord will give you work to do and He will bless you with rewards in return "a victor's garland which is imperishable."