“Once Saved Always Saved? Or, after the moment of grace, is a Christian then judged by his works and God’s holy law?”
That is NOT the question. Rather, can someone be a Christian and then CHOOSE to reject their own salvation?
Hebrews 6: “4 For it is impossible to renew to repentance those who were once enlightened, who tasted the heavenly gift, who shared in the Holy Spirit, 5 who tasted God’s good word and the powers of the coming age, 6 and who have fallen away. This is because, to their own harm, they are recrucifying the Son of God and holding him up to contempt.”
Romans 11: “17 Now if some of the branches were broken off, and you, though a wild olive branch, were grafted in among them and have come to share in the rich root of the cultivated olive tree, 18 do not boast that you are better than those branches. But if you do boast—you do not sustain the root, but the root sustains you.
19 Then you will say, “Branches were broken off so that I might be grafted in.” 20 True enough; they were broken off because of unbelief, but you stand by faith. Do not be arrogant, but beware, 21 because if God did not spare the natural branches, he will not spare you either.
22 Therefore, consider God’s kindness and severity: severity toward those who have fallen but God’s kindness toward you—if you remain in his kindness. Otherwise you too will be cut off. 23 And even they, if they do not remain in unbelief, will be grafted in, because God has the power to graft them in again.”
All Christians struggle with sin, those that say they don’t are lying (1John 1). Even the apostle Paul anguished over his (see Romans 7). What determines our salvation is what Christ has done for us and not how well we behave. That is not saying that we should not endeavor to obey, but that God’s grace through Christ ensures us that we are His. If He has chosen us, then He will complete His work of conforming us to the image of Christ. This may not be according to our own timing, and may or may not always be visible to us or others, specially those who are also blinded by the sin in their own lives and has zero bearing eternally. It is a waste of time to question other’s salvation, specially after they are gone, there is nothing to be gained by it.
Once Saved Always Saved means that he was saved.