I will assume you are speaking of “Once saved always saved”
St. James, in his epistle, gives the example of an erring believer and how he can be brought back: “Brethren, if any of you do err from the truth, and one convert him; Let him know, that he which converteth the sinner from the error of his way shall save a soul from death, and shall hide a multitude of sins” (James 5:19-20). “Any of you”! Note again that he is talking to people who are of the flock. If a Christian errs from the truth and is converted, the good man who helps him reaps these spiritual benefits.
James was speaking of someone already in Christ. So, why would a person already saved need to be saved from death, if once save always saved?
There is no way to work for salvation. It’s a gift from God. If it wasn’t a gift or conditional, He would have made that clear in his Word. If you have to work for it or to keep it, it’s not a gift. “Not by works lest any man should boast”.
The fact is that God hates pride and will not share His glory.
Other than belief in Christ as redeemer, what other conditions are necessary for salvation?
If you must produce fruit, how much and what fruit must you have?
Salvation and sanctification are very different. Salvation saves the believer from Hell. Sanctification is about judging the believer’s works for rewards and crowns. There is a crown for evangelism. You can gain it or not gain it.