More drill down on your definitions above:
Universalism: Universalism is the teaching that all people will be saved. Some say that it is through the atonement of Jesus that all will ultimately be reconciled to God. Others just say that all will go to heaven sooner or later, whether or not they have trusted in or rejected Jesus as savior during their lifetime. This universal redemption will be realized in the future where God will bring all people to repentance. This repentance can happen while a person lives or after he has died and lived again in the millennium (as some "Christian universalists" claim) or some future state. Additionally, a few universalists even maintain that Satan and all demons will likewise be reconciled to God.
https://carm.org/universalism-is
OSAS: "Once saved always saved" is the position that when a person becomes a
Christian he can never lose his
salvation. The debate on this teaching has been raging within Christian circles for centuries. Many believe it is possible to lose one's salvation, while others believe it is not. Both use the
Bible to support their beliefs.
https://carm.org/what-is-once-saved-always-saved
"OSAS" is IMO a modern term which has no basis in any creeds or confessions of faith. You may see such on some church websites in the statement of faith. What we are truly discussing is
The Perseverance of the Saints, which is described in the Westminster Confession of Faith:
CHAPTER XVII.
Of The Perseverance of the Saints.
I. They whom God hath accepted in his Beloved, effectually called and sanctified by his Spirit, can neither totally nor finally fall away from the state of grace; but shall certainly persevere therein to the end, and be eternally saved.
II. This perseverance of the saints depends, not upon their own free-will, but upon the immutability of the decree of election, flowing from the free and unchangeable love of God the Father; upon the efficacy of the merit and intercession of Jesus Christ; the abiding of the Spirit and of the seed of God within them; and the nature of the covenant of grace; from all which ariseth also the certainty and infallibility thereof.
III. Nevertheless they may, through the temptations of Satan and of the world, the prevalancy of corruption remaining in them, and the neglect of the means of their perseverance, fall into grievous sins; ad for a time continue therein: whereby they incur God's displeasure, and grieve his Holy Spirit; come to be deprived of some measure of their graces and comforts; have their hearts hardened, and their consciences wounded; hurt and prevalancy others, and bring temporal judgments upon themselves.
CHAPTER XVIII.
Of the Assurance of Grace and Salvation.
I. Although hypocrites, and other unregenerate men, may vainly deceive themselves with false hopes and carnal presumptions: of being in the favor of God and estate of salvation; which hope of theirs shall perish: yet such as truly believe in the Lord Jesus, and love him in sincerity, endeavoring to walk in all good conscience before him, may in this life be certainly assured that they are in a state of grace, and may rejoice in the hope of the glory of God: which hope shall never make them ashamed.
II. This certainty is not a bare conjectural and probably persuasion, grounded upon a fallible hope; but an infallible assurance of faith, founded upon the divine truth of the promises of salvation, the inward evidence of those graces unto which these promises are made, the testimony of the Spirit of adoption witnessing with our spirits that we are the children of God; which Spirit is the earnest of our inheritance, whereby we are sealed to the day of redemption.
III. This infallible assurance doth not so belong to the essence of faith but that a true believer may wait long and conflict with many difficulties before he be partaker of it: yet, being enabled by the Spirit to know the things which are freely given him of God, he may, without extraordinary revelation, in the right use of ordinary means, attain thereunto. And therefore it is the duty of everyone to give all diligence to make his calling and election sure; that thereby his heart may be enlarged in peace and joy in the Holy Ghost, in love and thankfulness to God, and in strength and cheerfulness in the duties of obedience, the proper fruits of this assurance: so far is it from inclining men to looseness.
IV. True believers may have the assurance of their salvation divers ways shaken, diminished, and intermitted; as, by negligence in preserving of it; by falling into some special sin, which woundeth the conscience, and grieveth the Spirit; by some sudden or vehement temptation; by God's withdrawing the light of his countenance and suffering even such as fear him to walk in darkness and to have no light: yet are they never utterly destitute of that seed of God, and life of faith, that love of Christ and the brethren, that sincerity of heart and conscience of duty, out of which, by the operation of the Spirit, this assurance may in due time be revived, and by the which, in the meantime, they are supported from utter despair.
http://www.reformed.org/documents/i....org/documents/westminster_conf_of_faith.html
This version has footnotes with Scripture proofs:
http://www.reformed.org/documents/wcf_with_proofs/index.html
I think it important we all understand the premise for many of these discussions including the OP.
Now for the OP:
The first question I would pose to the group is if Salvation, all of it----justification, sanctification and glorification---is God's Sovereign work? Or is it a mixture of God's will and man's will (semi-pelagianism) or can mankind keep the law perfectly (Pelagianism)?
From the three above stem all the ancient, modern and post-modern beliefs within and without Christianity reference salvation. Two of the above were condemned by early Church Councils. St. Augustine addressed and condemned Pelagianism; The Council of Orange condemned semi-Pelagianism.
That leaves us with Salvation as a Sovereign act of God.
