First thing, what is "buying and selling"? It is what we do everyday. So if people need to to be "marked" in order to buy and sell, what we looking at is some kind of "marked economy".
It stands to reason that for such a society to function like this, there has to be mechanisms in place that can determine that the people who take part in society have a "authentic mark" on them (that means there would have to be verification methods set up).
Look with credit/debit cards, each number is registered to a individuals account, but if someone was to try and use a card with a fake number and scan it through a machine, that is not going to work.
Now when looking in context of this word "worship" what are the people doing? Before the person accepts the mark, said person has to give their consent, and if they have given their consent, they have obeyed or submitted themselves to a higher authority to accept the mark so they can continue to be part of society. I suppose one can call this some kind of "2 factor authentication" to use a expression. The person has willingly complied with the requirement to get the mark and has accepted.
This "mark" whatever it is, is a "means of identification".
Now in the world we live in today, the reference to the right hand and forehead, maybe there is something inside the people who took the MOTB, something going through their blood stream and the locations mentioned could be referring to specialised scanning equipment? I also recall some time ago reading a article (I think one can still find it on the internet), of all the places in the body ideal for a implant, it was the right hand and forehead, something to do with the temperature in those locations.
Whatever it is, we are headed there, if we haven't got there already.
But what I have seen in the past 2 years, tells me we are much closer than we realise (for all I know, we could of been seeing a trial or test run of what the future will be like).
