Since all the Tribulation saints are beheaded (Rev 20),
You are wrong that Rev 20 speaks of "all" the trib saints. It only focuses upon that one group. There are others such as the two prophets and the 144k and the two candlesticks/churches, and those mentioned in the 5th seal.
you are suggesting that the entire Church will be beheaded. And that is pure nonsense.
It's nonsense because you wrongly came up with that conclusion. I never said it, nor is it true.
See Revelation 3:10.
See Rev 2:10 Fear none of those things which thou shalt suffer: behold, the devil shall cast some of you into prison, that ye may be tried; and ye shall have tribulation ten days: be thou faithful unto death, and I will give thee a crown of life.
Tribulation and death is promised. That's called checkmate.