I understand that once saved it is eternal. What if the people(s) who are saved and cannot be taken out of the hand of God take the mark? Also, I know that in Revelation Yeshua said that He will keep us from the hour of temptation. Can you explain these things, please?
From a careful reading of Rev. 14:12-13 it appears that eternal security (OSAS) is a blessing only given to the Church, which will be gone well before the command to take the mark is issued. Therefore post-Church believers will not be guaranteed eternal security. Instead they will be like Old Testament believers who had to remain faithful. Rev. 14:12 says they will have to obey the commandments and hold to the testimony of Jesus to remain saved, and will have to exercise patient endurance during this time. In Matt. 24: 13 Jesus said people will have to stand firm to the end to be saved.
In Rev. 14:13 John was told to write, “Blessed are those who die in the Lord from now on.” I think this means post Church believers will be expected to die rather than take the mark.
In Rev. 2-3 Jesus was writing to churches. In Rev. 3:10 He promised to keep true believers from the hour of trial (temptation) that is going to come upon the whole world to test those who live on the earth. This is a reference to the end times judgments. We know this because the end times judgments are the only time of trial scheduled to involve the whole world. The Greek word translated “from” in this verse literally means “out of the time, place, or cause” of the event, in this case the end times judgments. It’s a reference to the pre-tribulation rapture of the Church.