My question has to do with salvation during the Old Testament, New Testament, and during the tribulation. I am still a little confused about how people were saved in the Old Testament, and how they will be saved during the tribulation. I understand that in this age of grace, we are saved by trusting that Jesus died on the cross as a propitiation for our sins, but were the Old Testament patriarchs saved by believing on a coming savior, or did they have to meet certain behavioral requirements as well, in essence making it a type of faith-plus-works salvation? And will that also be the case for Tribulation believers?
Old Testament believers had to keep the commandments as evidence of their faith in a coming redeemer. The sacrifices they performed at the Temple were not sufficient in and of themselves to set aside their sins. They also had to believe those sacrifices represented the coming Messiah.
Those who come to faith after the Church is gone will also have to keep the commandments and believe in Jesus (Revelation 14:12, Revelation 16:15) .
This will be similar to the faith plus works doctrines practiced by some groups today.
Neither the pre-Church nor the post-Church believers are promised Eternal Security. This is a blessing only the Church enjoys.