Combined together in the order shown the Greek letters for 666 that John saw in his vision for the mark of the beast can symbolize sodomy just like 69 symbolizes mutual oral copulation.

χξς

The picture shows John viewing an ancient oil lamp from ancient Rome with two men engaging in sodomy, and Χξς depicted from an ancient manuscript.

Therefore it can be construed that the mark of the beast is the acceptance and condoning of sodomy; or as we know it in our modern day vernacular: homosexuality.

Is this plausible? Let us take a closer look.