But the one who stands firm to the end will be saved – Matthew 24:13
Some Christians believe that those who are faithful to Christ during the Tribulation will see eternal salvation. They say that this is an important sign that a Christian is truly saved.
They say that this is also a way to distinguish true believers from fake ones. They point to the stories of Lot, Samson and Solomon. These guys were lax in the middle of their life but they still persevered to the end.
Others think that this passage means that those who fall away from Christ will lose their eternal salvation. This is a hard concept to grasp because it contradicts other teachings of Jesus and the apostles.
Those who fall away will never go to heaven (John 3:17; Eph 2:8-9; Rom 1:16-17). They will never know peace or joy or be with God in eternity.
But the ones who remain faithful to Christ during the Tribulation will be physically saved, that is, they will survive the terrible events and be alive or delivered by Messiah when he returns at His Second Coming.
This could mean that those who fall away will lose their salvation or that apostasy will disprove claims of earlier faith. However, these interpretations are not the only possible meaning of this verse.