CathInfo.com

But the jab is not given "freely to those who want it". 

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What I mean is, anyone can go into a drug store and get the jab, and nobody verifies if you have worshiped the Beast before they give it to you. It's given to anyone who asks for it. The Mark of the Beast will only be given to people who have worshiped the Beast.

We need to remember that the words of Apocalypse 13 are primarily figurative, meaning not necessarily to be taken literally. 

"Apocalyptic" language should be read as pointing to a reality but cloaking that reality in metaphorical and allusive language. For example, the idea of "the Mark of the Beast" [Greek: charagma] is a literary allusion to Deuteronomy 6:4-9, which says:

4 Hear, O Israel, the Lord our God is one Lord.  5 Thou shalt love the Lord thy God with thy whole heart, and with thy whole soul, and with thy whole strength.  6 And these words which I command thee this day, shall be in thy heart:  7 And thou shalt tell them to thy children, and thou shalt meditate upon them sitting in thy house, and walking on thy journey, sleeping and rising.  8 And thou shalt bind them as a sign on thy hand, and they shall be and shall move between thy eyes.  9 And thou shalt write them in the entry, and on the doors of thy house.

Using literary allusion, St. John is saying that those who do this bad thing (receive "the Mark of the Beast") are those who love not "the Lord" but "the Beast" with their "whole heart, whole soul, and whole strength." 

Now, who/what is "the Beast?" I think it is a Counterfeit Bride of Christ that is wedded not to the God-Man, Jesus Christ, but to "the World." This Counterfeit Bride is also called "the Whore of Babylon" in the Apocalypse. The Whore is the symbol for all of those who claim the name Catholic Christian, but reject His teachings and instead follow the human teaching of a man who heads up the Counterfeit Bride, the "Bergoglian Church." These Catholics commit spiritual adultery by wedding themselves to the Beast ("the World") while their Bridgroom (Christ) is away prior to the Second Coming.

So while "the mark" is an actual literal thing. The description given using the figurative language of the Apocalypse should not necessarily be interpreted in a slavishly literal way. The vaccine passport or some future iteration is most likely "the mark." The vaccine passport cannot exist without the vaccine. So the vaccine should also be thought of as "the mark" or at least its precursor.

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I don't see the connection between the vaccine and worshiping the Beast? The vax pass is something given to you if you receive a drug; the Mark is something given to you if you worship the Beast. Those are two entirely different things.

One "worships" the "Beast" when they prioritize "worldly" things to "spiritual" things. Such as prioritizing one's bodily health over concerns about aborting innocent babies. That's just one example, but relevant to the vaccine issue.