The Bible tells us that the Mark of the Beast is placed in the forehead. The forehead in scripture represents the mind, the will, the seat of intelligence, it's where we make our decisions and give mental assent to something, so when it says the mark is received in the forehead it means that we willingly accept it.
Hebrews 10:16 "This is the covenant that I will make with them after those days, saith the Lord, I will put my laws into their hearts, and in their minds will I write them;"
It also says that the Mark of the Beast can be received in the right hand, this is because the right hand in the Bible represents co-operation, if we give our hand to it we not only accept and go along with it but we will co-operate with the beast power.
Ecclesiastes 9:10 "Whatsoever thy hand findeth to do, do it with thy might; for there is no work, nor device, nor knowledge, nor wisdom, in the grave, whither thou goest."
A person will be marked in the forehead by a decision to keep Sunday as a holy day. In fact, the frontal lobe is considered to be the very seat of your emotions and your ability to make judgments, the hand is a symbol of work, therefore, a person will be marked in the hand by working on God's holy Sabbath or by going along with Sunday laws for practical reasons (job, family, etc.). The sign, or mark, for either God or the beast will be invisible to people. You will, in essence, mark yourself by accepting either God's sign or mark, the true Sabbath, or the beast's mark, Sunday, the false sabbath. Though invisible to men, God will know who has which mark.
2 Timothy 2:19 "Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, let everyone that nameth the name of Christ depart from iniquity.
God knows who are His, this is why the Seal of God is not placed in the hand, it is placed only in the forehead, because there is nothing we can do to work our way to Heaven, and God will not force Himself upon us, He will only accept us if we love and trust in Him. The only way to gain entrance to Heaven is through Christ and all He has done for us; the devil on the other hand will take us any way he can get us - we can work our way to Hell but not to Heaven.
Revelation 14:9-12 "And the third angel followed them, saying with a loud voice, If any man worship the beast and his image, and receive his mark in his forehead, or in his hand, 10 The same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation; and he shall be tormented with fire and brimstone in the presence of the holy angels, and in the presence of the Lamb: 11 And the smoke of their torment ascendeth up for ever and ever: and they have no rest day nor night, who worship the beast and his image, and whosoever receiveth the mark of his name."
Here we see the tragic consequences of those who accept the Mark of the Beast, but what about the people who do not receive the Mark of the Beast, but through love and trust in God receive the Seal of God?