I believe that 666 is a symbol for deception and practicing deceit and falsehood.
To carry the mark on the forehead is to be blind to God’s Justice.
To carry the mark on the right hand, is to know God’s Justice but lie about it or refuse to practice it.
A Christian who supports Trump carries the mark of the beast on his forehead by being ignorant of God’s morals and value systems.
An atheist who intentionally slanders somebody they know is harmless or plays with somebody else’s dignity and reputation carelessly and recklessly, carries the mark on their right hand.
Both are offensive acts of deception, both those who believe deception or practice deception, those ignorant of the truth or refuse to practice the truth, carry the mark of the beast.
When Jesus said many are called but few are chosen it means the majority either do not know the truth or know the truth but refuse to practice it but falsehood can be removed with time and dedication and patience and truth is contagious so a small group of honest people can make a whole community honest.