If someone takes the mark of the beast they are going to hell and that's a belief shared by many Christians, yes? So many give so much power to Satan believing he has the power to seal someone until their destruction, to hell they go, and so be it, no question. If someone has the seal of the Holy Spirit until the day of redemption, why is this not believed? It sounds to me as though more faith is given to the devil then the Holy Spirit. Is the devil more powerful than God? Hell no and all Christians will agree.
The devil likes to duplicate, to copy because he can't come up with anything original. When Cain killed Abel, the devil watched God mark Cain with a seal on his forehead. God didn't kill Abel, blood for blood, there was no "thou shalt not kill" at that time and where there is no law there is no transgression, Romans 4:14. Killing Abel was a sin, sin was in the world from Adam to Moses but sin was not imputed where there is no law, Romans 5:13. So what was God to do? Mark Cain with a seal. Ask yourself this, if you are a professing Christian, a believer, are you under the Law or Grace? Romans 6:13. As a child of God, no matter what you do, what "sin" you commit, you are sealed, you are His, Ephesians 1:13, 2 Corinthians 1:22, and the devil is hoping you don't know that and because he is such a skilled liar (give credit where's its due), John 8:44, and wants to attack you and make you doubt, the only weapon of destruction he has to use against you is the Law, Galatians 3:1.
This is where repentance and confession come in, which are different topics for discussion and mainstream Christianity has got this all wrong too. The devil has his finger in every pie, 2 Corinthians 2:11.