Who are the 144,000 and how do they relate to the Church as a whole during the tribulation period? Do they get raptured before, with, or after us? To what purpose do they serve?

The 144,000 are found twice in the book of Revelation – first at the 6th seal and again at the end of the 70th week standing on Mt. Zion. They are distinctly Jewish and they are sealed immediately preceding the rapture. I believe that Jewish believers in Messiah Yeshua will also be raptured. Therefore, these are Jewish non-believers who will be protected for the latter 3 1/2 years and have the opportunity to accept Jesus as Messiah as the Lord Jesus meets with them in the wilderness of Edom.