Mary was a believer, these terms are not applicable to a believer after conversion.
giving thanks unto the Father, who made us meet to be partakers of the inheritance of the saints in light; who delivered us out of the power of darkness, and translated us into the kingdom of the Son of his love; in whom we have our redemption, the forgiveness of our sins COL. 1:12-14
This is one of the major differences between Catholic Christians and Protestant Christians. We do not believe that "once saved, always saved" in the sense that a Christian can still sin but automatically go to human because he has accepted Jesus into his heart as his "personal Lord and Savior."
Yes, Jesus is my personal Lord and Savior and I have the hope that if I live my life in accordance with His Commandments, seek forgiveness for my sins, and strive to be more like Christ, that through the grace of God I may join Him in Heaven. But it's not a given. Remember, even the demons believe.
1 Timothy 4There are many more references to the importance of living a life for and like Christ, in persevering until the end, etc. I think this means that we can ALL fall and in the end, we still have to answer God on Judgement Day for our faith and our actions.
16Watch your life and doctrine closely. Persevere in them, because if you do, you will save both yourself and your hearers.Hebrews 10:
26If we deliberately keep on sinning after we have received the knowledge of the truth, no sacrifice for sins is left,
27but only a fearful expectation of judgment and of raging fire that will consume the enemies of God.
28Anyone who rejected the law of Moses died without mercy on the testimony of two or three witnesses.
29How much more severely do you think a man deserves to be punished who has trampled the Son of God under foot, who has treated as an unholy thing the blood of the covenant that sanctified him, and who has insulted the Spirit of grace?
30For we know him who said, "It is mine to avenge; I will repay," and again, "The Lord will judge his people."
31It is a dreadful thing to fall into the hands of the living God.36You need to persevere so that when you have done the will of God, you will receive what he has promised.
Matthew 10
22All men will hate you because of me, but he who stands firm to the end will be saved.
God bless.