If one believes it can be "taken back," then he/she believes it is up to him/her to "do" in order to stay saved. The Gospel is a Gospel of God's grace. If we don't understand grace, that we are saved only by the faith God provides us through His grace, that Christ's death and resurrection are all-sufficient for salvation and eternal life, then we don't understand the Gospel, and there is at least a chance we are not saved. How can that be? Not believing the whole of the Gospel of grace means we have not believe the truth. That's why we care.
But try to think about it. If he had his salvation and just afraid that it would be taken back if he does not do good, it didn't really matter, did it? We try to do good because God is good. Both groups are trying to do good.
If after being saved, the revelation he received is try your best to be good to retain your salvation, then so be it.
Failure to believe any part of the Bible is a failure to understand God's word. Failing to understand God's word is again, a reason to question if one actually knows the truth, or some manmade doctrine. There is only one Mediator between God and man (1 Timothy 2:5). He lives forever to make intercession for us (Hebrews 7:25). He assures us that whatever we ask in His name, He will do (John 14:13, 14). And King Saul got in a lot of hot water with God trying to contact the dead (1 Samuel 28). Praying to the saints is contraindicated by Scripture.
Think about it. Are you saying if we fail to understand God's Word, it will affect our salvation. How is it different from saying " we have something to do to our salvation?"
Paul laid out very specific guideliness for church leadership to Timothy and Titus in his pastoral letters. Anything outside of those guidelines is unbiblical.
Just remember the disagreement of Paul and Peter. And remember, you and I both believe Paul and Peter are both saved.
Again, biblical guidelines call for immersion.
Would that really affect our salvation. Remember the thief to whom Jesus said, " Assuredly, you will be with Me in paradise". He didn't get baptized.
We need to be able to communicate consequences to the unbeliever. He/she needs proper information that will make them amenable to the Gospel.
I truly believe that if he can sincerely and honestly accept Jesus as his savior and repent his sins, he is no longer an unbeliever.
Man-made ideas are the enemy of the Gospel, and we who believe are not affected by them. But our job isn't just to be satisfied in our own gift of God's grace, but help others understand it so they, too, can receive it.
But don't you think once they get saved, the Holy Spirit will guide them to whatever is the right interpretation of the Bible? Should we rely on ourselves or the Holy Spirit?