‘For look, the Day is coming, glowing like a furnace. All the proud and all the evil-doers will be the stubble, and the Day, when it comes, will set them ablaze, says Yahweh Sabaoth, leaving them neither root nor branch. But for you who fear my name, the Sun of justice will rise with healing in his rays, and you will come out leaping like calves from the stall. — Malachi 3:19-20
The prophet Malachi is foreshadowing the destruction of the Temple in Jerusalem, and also possibly the end-times when Jesus Christ will return.
Our relationship with our Lord is a covenant. He promised to be our God, and we promise to be his people. That entails doing certain commands (the ten commandments, the Great Commission, the Precepts of the Church, the corporal and spiritual works of mercy, prayer without ceasing). Proper fear of the Lord moves us to do these things. If we do as we ought, we can have great hope that we will be saved.
This doesn’t mean that it will be easy. Our Lord warns in the Gospel reading for today that there will be persecutions:
“But before all this they will lay their hands on you and persecute you, delivering you up to the synagogues and prisons, and you will be brought before kings and governors for my name’s sake. This will be a time for you to bear testimony. Settle it therefore in your minds, not to meditate beforehand how to answer; for I will give you a mouth and wisdom, which none of your adversaries will be able to withstand or contradict. You will be delivered up even by parents and brothers and kinsmen and friends, and some of you they will put to death; you will be hated by all for my name’s sake. But not a hair of your head will perish. By your endurance you will gain your lives.” — Luke 21:12-19
Those who persevere to the end will be saved. Remember St. Paul, “I have fought the good fight, I have won the race, I have kept the faith…now I will receive my crown of glory”.