OSAS - Once Saved, Always Saved affirms that the moment a person places their faith in Jesus Christ as their “personal Lord and Savior” (or some variant of this phrase), and believes He is the Son of God, their salvation is guaranteed, and nothing they do or say can change this reality.
Here are some objections that are note worthy:
Protestants misunderstand Salvation as a "instance in time"
salvation is a 3-dimensional reality with past, present, and future componets:
he saved us, not because of righteous things we had done, but because of his mercy. He saved us through the washing of rebirth and renewal by the Holy Spirit,
even when we were dead in our transgressions, brought us to life with Christ 5 (by grace you have been saved), raised us up with him, and seated us with him in the heavens in Christ Jesus, that in the ages to come he might show the immeasurable riches of his grace in his kindness to us in Christ Jesus. For by grace you have been saved through faith, and this is not from you; it is the gift of God;
1 Cor. 1:8
He will keep you firm to the end, irreproachable on the day of our Lord Jesus (Christ).
2 Cor. 2:15
For we are the aroma of Christ for God among those who are being saved and among those who are perishing,
How much more then, since we are now justified by his blood, will we be saved through him from the wrath. Indeed, if, while we were enemies, we were reconciled to God through the death of his Son, how much more, once reconciled, will we be saved by his life.
1 Cor. 3:12-15
If anyone builds on this foundation with gold, silver, precious stones, wood, hay, or straw, the work of each will come to light, for the Day will disclose it. It will be revealed with fire, and the fire (itself) will test the quality of each one’s work. If the work stands that someone built upon the foundation, that person will receive a wage. But if someone’s work is burned up, that one will suffer loss; the person will be saved, but only as through fire.
If OSAS were true, what is the point of God’s judgment after you die?
OSAS is at odds with what St. Paul teaches since the Saint says,
And do this because you know the time; it is the hour now for you to awake from sleep. For our salvation is nearer now than when we first believed
First believed in what? This is SAINT PAUL telling you that his “initial belief” has made his salvation “closer”; not that it has been sealed for eternity.
And lastly, OSAS is anti-biblical since you KNOW heaven is “yours” after you have been "saved"
For in hope we were saved. Now hope that sees for itself is not hope. For who hopes for what one sees?
*sidenote: if I were a protestant woman, I would not use contraception since clearly the scriptures teach,
1 Tim 2:15
But she will be saved through motherhood, provided women persevere in faith and love and holiness, with self-control.
yet, anther reason why contraception is wrong…it blocks, in an unnatural way, a path of salvation for women.