So, 80 percent of the us will be raptured (I think around 80 percent of America believes in Jesus).
Believing in Jesus is not enough. Demons believe in Jesus, and shudder in fear.
You are only saved when you confess your need to Him and accept Him as your Saviour.
Are you sure you live in the same America that I do? I would be surprised if even 20% of all Americans are born again Christians. A majority of the mainline Protestant churches are liberal, apostate false churches that preach a false works salvation and a social gospel, and a quarter of the others are just nice social clubs. Based on my experience and conversations with Catholics, IMHO more Catholics are only nominal Christians than are true believers in Jesus Christ, which is probably about the same ratio as mainline Protestants. If you don't believe it just ask yourself why the states that are most heavily Catholic are also among the strongest supporters of abortion "rights" when the Catholic Church itself is the most vocal opponent of abortion in the world.
Add all that up and throw in the millions upon millions of Americans who don't even make a pretense of being Christian and you are left with a small minority of the population, both Protestants, evangelicals, and Catholics, who are true believers in the Gospel of Christ. The bible says that by their works we shall know them, "them" being true Christians. We aren't saved by our good works, but if we are saved by grace through faith in the risen Lord Jesus Christ our works will show it.