What happens to people who take the mark of the beast?
Those who take the mark of the beast seal their eternal doom before God and have no further opportunity for salvation. They may get along with the powers that be, having submitted to the Antichrist's rule and the religious system demanding the mark, but they forfeit any chance of salvation.
Les explains that the mark of the beast is simply those who have given in to the rule of the Antichrist and to the demands of the religious system that will absolutely demand they have it. He notes that if they take it, they may get along with the powers that be, but they seal their eternal doom so far as God is concerned, and they have no more opportunity for salvation.