I had a cashier explain to me that bar codes are the mark of the beast

Not by a cashier, but a Pentecostal woman, who asked what my faith was and I told her,” I didn’t have a faith. I worship no Gods or Goddess.” All she did was tell me,” I will pray for you.”

How is getting a job at Walmart even consider to be a blessing? How is having to shop there a blessing either?
Frankly if that happened to me at any store I would call out the manager, as it is totally disrespectful and an attack on peoples beliefs. Here in Canada it may even be an attack on one Charter Rights.
Of course here Walmart is noted for hiring the stupidest of people; you know the one that actually get off on doing the Wally Squiggly.

Not in a store, but I did when I was in the hospital recovering from quadruple-bypass surgery.

I worked at Walmart for 7 months as a greeter. The store was in a small town that serviced many small towns (in other words - hick towns). One woman wanted to pray for me. I said "sure," thinking I would be put on a prayer chain or something like that. But noooooooooo. She put her hand on my shoulder and prayed out loud. I was horribly embarrassed. Later in the break room, I mentioned the incident and how I thought it was inappropriate. The comments I received from other employees started with, "Well, I'm a Christian and it wouldn't bother me." They could not understand why anyone would object to this. Since Trump was elected, I have gone back into the closet. With the blue-collar people I work with, if they ask me my religion (which they shouldn't), I tell them I'm Jewish. Because Bible Belt Christians love Jews - they feel sorry for us because we don't have Jesus. But if I said "atheist," they would be terrified.

As I never shop at Wal-Mart, it isn't going to happen. Just don't go there.

Talk to his manager. No need to avoid the store just because of one inappropriate comment by one mannerless person.