"The Lord Knows Them That Are His:" The Sealing of the 144,000

Who are the 144,000 in Revelation 7? They are the complete number of the elect known only to God (7:1-8), and the "great multitude, which no man could number" (7:9-17) who have been sealed with their Father's name in their foreheads, washed their robes and made them white in the blood of the Lamb, and "come out of great tribulation" - a tribulation which has been oppressing them for the last 2,000 years.

But will only 144,000 ultimately be saved?