I believe that ultimately, people are responsible for their own actions and decisions (we are free moral agents). There is a pastor and church (I think it is in Miami) that tatoos 666 on themselves. There are many strange beliefs today (there always were, but many more are becoming popular these days because daily life is not so 'fulfilling' as it used to be).
Since WE HAVE BEEN TOLD that accepting the mark of 666 on our RIGHT hand or FOREHEAD is DEFIANCE (rebellion against) of The Lord, we would be WITHOUT EXCUSE if we allowed any wordly mark to be put on our right hand or forehead. If nothing else, that mark would have a philosophical effect (it would symbolize our defiance of The Lord and we would begin to behave accordingly, and "be decieved").
Your decision is yours to make (we are free moral agents). Choose today whom you shall serve, God or Mammon. Everyone who chooses to live their life in a manner that they become a part of "death" or "Hades" will end up in the Lake of Fire.