Sin is the only way (I can think of) that a saved person can lose their salvation.
but now that you have come to know God, or rather to be known by God, how can you turn back again to the weak and destitute elemental powers? Do you want to be slaves to them all over again? (Gal. 4:9)
For freedom Christ set us free; so stand firm and do not submit again to the yoke of slavery. It is I, Paul, who am telling you that if you have yourselves circumcised, Christ will be of no benefit to you. Once again I declare to every man who has himself circumcised that he is bound to observe the entire law. You are separated from Christ, you who are trying to be justified by law; you have fallen from grace.(Gal 5:1-4)
This warning applies to those who are connected to Christ in faith. We can be in Christ, then be severed from Him and fall away from God’s grace. You cannot be severed from something unless you were previously connected to it.
**Now I am reminding you, brothers, of the gospel I preached to you, which you indeed received and in which you also stand. Through it you are also being saved, if you hold fast to the word I preached to you, **unless you believed in vain. (1 Cor 15:1-2)
Working together, then, we appeal to you not to receive the grace of God in vain.
(2 Cor 6:1)
we can receive the grace of God then choose not to cooperate with it. (Lose our salvation)
Do you agree that all Christians grieve the Spirit and sin against God as adopted children? When you take the apostasy verses such as Hebrews 6, there is no return to the Faith. So, at one point does a Catholic loose their salvation? And once you are no longer ingrafted into Christ, can you return to the Faith according to Roman Catholic doctrine? If a Catholic falls away and is reunited to Christ, is this considered a second new birth?
Hebrews 6
6:1 Therefore let us leave the elementary doctrine of Christ and go on to maturity, not laying again a foundation of repentance from dead works and of faith toward God, 2 and of instruction about washings, [1] the laying on of hands, the resurrection of the dead, and eternal judgment. 3 And this we will do if God permits. 4 For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, 5 and have tasted the goodness of the word of God and the powers of the age to come, 6 and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt. 7 For land that has drunk the rain that often falls on it, and produces a crop useful to those for whose sake it is cultivated, receives a blessing from God. 8 But if it bears thorns and thistles, it is worthless and near to being cursed, and its end is to be burned.
9 Though we speak in this way, yet in your case, beloved, we feel sure of better things—things that belong to salvation. 10 For God is not unjust so as to overlook your work and the love that you have shown for his name in serving the saints, as you still do. 11 And we desire each one of you to show the same earnestness to have the full assurance of hope until the end, 12 so that you may not be sluggish, but imitators of those who through faith and patience inherit the promises.
Gal 2
11 See with what large letters I am writing to you with my own hand. 12 It is those who want to make a good showing in the flesh who would force you to be circumcised, and only in order that they may not be persecuted for the cross of Christ. 13 For even those who are circumcised do not themselves keep the law, but they desire to have you circumcised that they may boast in your flesh. 14 But far be it from me to boast except in the cross of our Lord Jesus Christ, by which [2] the world has been crucified to me, and I to the world. 15 For neither circumcision counts for anything, nor uncircumcision, but a new creation. 16 And as for all who walk by this rule, peace and mercy be upon them, and upon the Israel of God.
17 From now on let no one cause me trouble, for I bear on my body the marks of Jesus.
18 The grace of our Lord Jesus Christ be with your spirit, brothers. Amen
I hope we all understand that circumcision is an Old Testament Sacrament.