There are three distinct and separate views of OSAS.
1. Antinomianism --- view that one can be sinful, fornicating, drunk, robbing, but still saved.
2. Predestined-Election --- view that God CHOOSES only a few; those chosen,
will be saved, the rest are beyond hope. Also called "irreisistlbe grace", "limited atonement", "Calvinism", "Reformed theology", "unconditional election", etc.
3. Eternal Security --- differs from #2, in that
everyone CAN be saved; but once "in", either their hearts are too changed to ever LEAVE, or God dynamically interferes to prevent one from leaving.
Ironically, though #1 is "easy to disprove", the other two frequently use terms like "backslidden-saved"; which, if you think about it,
is nothing but Antinomianism revisited.
I've (mostly) written a text on the subject; citing all the verses the propopnents have given me, and explaining how they can exist in a "OSNAS" view. Then there is a section that I do not think any OSAS view will be able to accommodate. It ismy view that salvation cannot be "lost"; but it can be "forfeit", by unbelief (faithlessness).
The question that binds all FOUR beliefs, three OSAS and one OSNAS, is: "What is salvation"?
This is a critical question; for it defines who and what we are.
Salvation is by belief (Jn3:16); but not any KIND of belief, for even DEMONS believe (James2:19). Jesus
qualified what kind of belief saves us --- belief that "causes us to be humbled as children" (Matt18:3-4), that causes us to be "dong God's will" (Matt7:21), to be "repentant" (Lk13:3), and to be "born again". Each of these is written as: "Unless ____, you won't go to Heaven".
The idea of "born again" is the umbrella
under which all the others reside. All the world has HEARD the term --- but what does it MEAN?
Salvation, in a single succinct word, is FELLOWSHIP with God! 1Jn1:3, 6-7. The real person of Jesus, and the person of the Holy Spirit --- these
indwell the believer. "Born again" is explained beautifully in Romans, chapters 6-8. It is "dead to sin, and alive by the Spirit in Christ". We are "new creations", the old "passes away annd all becomes new" (2Cor5:17). We are "crucified with Christ, no longer WE who live but Christ lives in us; and the life we now live in the flesh, we live by faith in the One who loved us and delivered Himself up for us." (Gal2:20)
RE "backsliding" -- Paul says, Rom6:1: "Shall we continue in sin that grace may abound? May it never be! How shall we who have DIED to sins,
still live IN it?" Many passages detail how the unrighteous live; and boldy assert that "those who practice such things will NOT go to Heaven; but YOU --- were as them, but now are WASHED, are SANCTIFIED, and JUSTIFIED in the name of Jesus and in the Spirit of our Lord." (1Cor6:9-11)
If all of us agree on the ESSENCE of salvation, as I have just stated, specifically FELLOWSHIP ---- which requires TIME --- prayer, reading the Word, fellowshipping and worshipping our Lord,
then the "OSAS/OSNAS" debate becomes non-issue, doesn't it?
We can all fellowship in harmony and worship God together.
PS: My book has an appendix of 40+ verses, and three summarized letters, that I feel really speak against OSAS; if you're interested, I can PM them to you...