I am having this same problem with my son. This is the way it was taught to me. My son just ignored me, I don’t think he was ready to hand over his Get out of Hell free card, but you are willing to give it a shot.
The Church teaches in agreement with Scripture that Christians “have been saved” through faith and baptism (Mark 16:16; Eph. 2:8-9; Romans 6:3-4), they’re “being saved” through cooperation with grace (I Cor. 1:18, I Cor. 15:1-3; II Cor. 6:1), and that they “shall be saved” if they persevere in the Faith (Matt. 10:22; Romans 2:6-7; Gal. 6:7-9).
Mark 16:16 He who believes and is baptized will be saved; but he who does not believe will be condemned.
Ephesians 2:8-9 For by grace you have been saved through faith; and this is not your own doing, it is the gift of God— 9 not because of works, lest any man should boast.
Romans 6:3-4 Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried[a] therefore with him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
1 Corinthians 1:18 For the word of the cross is folly to those who are perishing, but to us who are being saved it is the power of God.
1 Corinthians 15:1-3 Now I would remind you, brethren, in what terms I preached to you the gospel, which you received, in which you stand, by which you are saved,** if you hold it fast**—unless you believed in vain.
For I delivered to you as of first importance what I also received, that Christ died for our sins in accordance with the scriptures,
2 Corinthians 6:1 Working together with him, then, we entreat you not to accept the grace of God in vain.
Matthew 10:22 and you will be hated by all for my name’s sake. But he who endures to the end will be saved.
Romans 2:6-7 For he will render to every man according to his works: **to those who by patience **in well-doing seek for glory and honor and immortality, he will give eternal life;
Galatians 6:7-9 Do not be deceived; God is not mocked, for whatever a man sows, that he will also reap. For he who sows to his own flesh will from the flesh reap corruption; but he who sows to the Spirit will from the Spirit reap eternal life. And let us not grow weary in well-doing, for in due season we shall reap, if we do not lose heart.
I hope this helps. I bolded the key words of the verses that point to past, present and future.
Matthew 19:26