There are two phrases in the form of a subject that have no active verb but two participles used as nouns. One in translated as "which/they devour" and the other as "the same shall receive" and "these men will be". The phrases are literally "the ones devouring" and "those getting" but since both words in these phrases are in the same form as subjects, they can be equated with the verb "to be". "These onse are devouring" and "Those are getting".
The word translated as "shew/show" is an uncommon word meaning "motive" or "pretext". Here, "justification" works a little better.
The word translated as "damnation" and "be punished" is the Greek word usually translated as "judgment". The line is the punchline and has two meanings depending on how we want to hear it. This line is: those are getting an excessive judgment. This can either mean they are going to get an excessive punishment, which is how the translators read it or that they are getting more of a compensation than they deserve. Both seem intended, but the translators didn't like the second meaning so they made the verb the future tense, which it isn't, and the judgment a punishment, which it isn't.