During the seven-year Tribulation, when the antichrist is in power, He will force everyone to take the mark of the beast and worship his image or be executed. Revelation 13:16-17 says, “And it was given to him [the antichrist] to give breath to the image of the beast, so that the image of the beast would even speak and cause as many as do not worship the image of the beast to be killed. And he causes all, the small and the great, and the rich and the poor, and the free men and the slaves, to be given a mark on their right hand or on their forehead, and he provides that no one will be able to buy or to sell, except the one who has the mark, either the name of the beast or the number of his name” [emphasis mine].
Unfortunately, those who comply with the Antichrist’s demands and receive the mark of the beast cannot and will not be saved—not because Jesus is unwilling or lacks a desire to redeem them from their sinfully depraved state—but because they refuse to surrender to Him and, instead, pledge their allegiance to the Antichrist by taking his mark and worshipping his image. Their continued refusal to repent ultimately seals them in their rebellious and idolatrous condition, guaranteeing them God’s judgment and wrath instead of redemption.
For this reason, Revelation 14:9-11 issues a sober warning in advance to warn of the danger of receiving the antichrist’s mark. It states, “Then another angel, a third one, followed them, saying with a loud voice, ‘If anyone worships the beast and his image, and receives a mark on his forehead or on his hand, he also will drink of the wine of the wrath of God, which is mixed in full strength in the cup of His anger; and he will be tormented with fire and brimstone in the presence of the holy angels and in the presence of the Lamb. And the smoke of their torment goes up forever and ever; they have no rest day and night, those who worship the beast and his image, and whoever receives the mark of his name.’”
On the flip side, everyone who refuses to take the mark and turns to Jesus for forgiveness and salvation will be redeemed and go to Heaven, despite suffering the antichrist’s promise of execution. John wrote in Revelation 7:14-15 after seeing a great multitude before God’s throne in Heaven, “These are the ones who come out of the great tribulation, and washed their robes and made them white in the blood of the Lamb. Therefore they are before the throne of God, and serve Him day and night in His temple. And He who sits on the throne will dwell among them.”
However, those who refuse the mark but also refuse to repent of their sins and reject Jesus’ offer of salvation will suffer the antichrist’s promise of execution and, ultimately, God’s righteous judgment and wrath on Judgment Day, along with all those who died in their sins.
I hope this brief synopsis helps you understand why those who receive the mark of the beast cannot be saved.