Is God the same yesterday, today, and forever? Can He make different rules for different folks in time concerning their salvation? Can He change the rules for salvation? What happens to one that looses ones faith today verses yesterday or tomorrow? What happened to Saul? Is the whole council of God for different times in History, or is it for all ages? I am confused by your applying the 10 virgins to the tribulation saints, I can not find that applied to them as being the bride of Christ. I am also confused that the parable of the vine dresser is not applied to the Church. Did not Jesus give this to the first members of His church?
The rule for salvation has always been the same. Only through faith in the Redeemer can man be saved. But the Bible is clear, with Saul being the prime example, that before the cross the Holy Spirit could be taken away. Ephes 1:13-14 says that can’t happen to us, but Rev. 14:12 and Rev. 16:15 indicate this will be true again during the Great Tribulation. Eternal Security is a gift given only to the Church.
Because the parable of the 10 virgins is placed in the time just after the 2nd Coming, the only way to believe it’s about the Church is to deny any kind of Rapture, whether pre, mid or post-trib.
The story of the vine dresser (John 15:1-8) is about the Church but it’s not about salvation, because salvation is not a fruit bearing event. The Lord’s point was that as believers we can only be fruitful when we’re working in His strength. When we go off on our own we’re not worth anything but are like the unfruitful branches the vine dresser throws in the fire. Notice He didn’t say we would be thrown in the fire but that we’re like unfruitful branches, of no value.