Mark of the Beast

Is the 'mark of the beast' a physical mark, or can the mark symbolize our 'thoughts and deeds'?
Some radical racists have used the bible to say that blacks are decendants of Cain, who slew Able in the Garden of Eden, because Cain's decendants were forever 'marked' and outcast from the rest of society.
The Mormons even used this belief to ban blacks from entering the temple until they lifted that ban in recent decades.
Some black Christians have implyed that the opposite is true, that mankind was originally black and through God's curse of 'vitiligo' did Cain's decendants turn white.

Wikipedia says:
As an act of irony, the curse by God focused strictly on neutralizing the benefits of Cain's primary skill, cultivating crops. When Cain complained that the curse was too strong, and that anyone who found him would kill him, God responded, "Not so; if anyone kills Cain, he will suffer vengeance seven times over",[3] and God "set a mark upon Cain, lest any finding him should kill him" (Gen. 4:15).

Revelations says:
“If anyone worships the beast and its image and receives a mark on his forehead or on his hand..."
And Revelations also goes on to say:
"Also it causes all, both small and great, both rich and poor, both free and slave, to be marked on the right hand or the forehead, so that no one can buy or sell unless he has the mark, that is, the name of the beast or the number of its name. This calls for wisdom: let the one who has understanding calculate the number of the beast, for it is the number of a man, and his number is 666."

666 literally translates into: Nero Ceasar - which literally translates into: Powerful Dictator.

Revelations 17:8 tells us that those people on earth (at the end-times) whose names were not written in the 'book of life', will be very shocked to find out the true identity of the beast is a person  that was, and is not, and yet is.

Obviously, this 'beast' controls the buying and selling of the global 'free market system'.
'Worshiping the beast' and 'it's image', and 'receiving a mark'.  Sounds like all three might be required, perhaps?  This mark sounds like the 'seal of endorsement' stating that the person 'belongs' to this belief system.  Thoughts, philosophy, etc. might be translated into 'forehead' and deeds, things done, carried out by, etc. may be the 'right hand'.  ("Did you have 'a hand' in this?"  "You are my 'right-hand' man." For examples.)
Nevertheless, there are people who literally do get the 666 tattooed onto their bodies.  As seen here.

The bible makes it clear that God's love and grace is inclusionary:
"There is neither Jew nor Greek, slave nor free, male nor female, for you are all one in Christ Jesus." -Galatians 3:28