http://www.fivedoves.com/letters/apr2007/dianeg430-1.htm

I agree. Another point is that Christians don't "buy" oil since the Holy
Spirit is part of the free gift of salvation. But the Tribulation saints
must "buy" oil. That is a very important point - people are not saved by
a permanent free grace situation in the tribulation. Those people must
endure to the end, must avoid taking the mark of the beast, must treat
the Jews well, and must love not their lives unto death (be willing to
get killed for the testimony of Jesus). It is a works and faith combined
situation for them. They can't say "once saved always saved" as
Christians can in this dispensation.