"The thing of greatest importance here is the awful fact that, before ever man’s HAND was extended and the transgression committed, that old serpent, the king of the bestial system, the devil, had IMPARTED HIS MIND TO THEM. The MARK OF THE BEAST was in their hearts, in their MINDS, and in their FOREHEADS, and what they did afterward was the MARK OF THE BEAST in their HANDS. It is not difficult to see that the things which men are doing today and have done in ages past are but the MANIFESTATION of that which is in their minds, for, “As a man THINKS in his heart, so is he” (Prov. 23:7) and “a good man out of the good treasure of the heart brings forth good things; and an evil man out of the evil treasure brings forth evil things” (Mat. 12:34-35). The mark of the beast that appears IN THE HAND (outward actions) is the direct result of the mark of the beast IN THE FOREHEAD (mind, nature). This is the mind that inspires the ever increasing confusion and violence that is running rampant among all nations."
In depth study on the mark in the link:
https://www.kingdombiblestudies.org/antichrist/antichrist1.htm#6
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Brain swab?
"The deep and hidden mysteries of God are never discovered by the investigations or probings of the natural mind because they pertain to a realm beyond the reach of the natural. Only by the spirit of wisdom and revelation from on high can we perceive the depth of meaning contained in the counsel of the Lord to Moses as He continued to instruct him respecting the observance of the Passover. “And it shall be when your son asks you in time to come, saying, What is this? that you shall say unto him, By strength of hand the Lord brought us out from Egypt, from the house of bondage: and it came to pass, when Pharaoh would hardly let us go, that the Lord slew all the firstborn in the land of Egypt ... and it shall be FOR A TOKEN UPON YOUR HAND, and FOR FRONTLETS BETWEEN YOUR EYES: for by strength of hand the Lord brought us forth out of Egypt” (Ex. 13:14-16). Again, the mark upon the hand and the forehead; not a little plastic card, or a brand or tattoo upon their flesh, but a taking into their MIND of the law of the Lord and a binding upon their hands - the OUTER ACTIONS - bespeaking the fulfilling of His law in all their doings."
https://www.kingdombiblestudies.org/antichrist/antichrist1.htm#7
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"But Christ, our spiritual heavenly Man, has purchased us with His blood, and paid a price for His sheep, and has SEALED US WITH HIS SPIRIT, and set HIS MARK upon us, so that we are His, and not our own, and are at His ordering and disposing by His heavenly power. And He orders us heavenly water and milk and wine and honey, and heavenly bread and meat, and the heavenly clothing, the fine linen of the righteousnesses of saints, and feeds us in His heavenly pastures of divine understanding, wisdom, and revelation. And so we are to live to Christ, the heavenly Man, and serve Him, and do all His will, and so know His doctrine; and so we come to know our Master’s crib, and know our Owner, and His heavenly life that has purchased us, and His heavenly voice that speaks to us and directs all our doing, and are not like the common ox or ass, that know not their owner, nor their master’s crib."
"My deep and earnest prayer is that the Lord shall give all His elect understanding, that they may be flooded with His light, and in His light see their Owner, and His crib, and Him that has purchased them, even the heavenly Man, the firstborn Son, the forerunner who for us has entered in beyond the veil. And is it not fit, O man, that the heavenly Man should have them whom He purchases, and has paid a price for them, at His service, and to be at His ordering and rule, and to live unto Him, and do His will, and not at the command and order of the bestial system of this world, be it political, economic, or ecclesiastical? My ransomed spirit shouts, Amen!"