Is Salvation During Tribulation Possible....?

Revelations tells us that there will be converts during the tribulation, as well as the millenium. One reason satan is loosed at the end of the millenium...to prove the true converts from those who claim to be such...God has always promised that true believers will be tested and proved since it's easy to believe in God when everything is great and much harder when life is difficult, harder still when life is threatened.