As several have pointed out the present active indicitave verb form's usage in Greek to indicate an on going action, I would like to point out just how easy it is to twist scripture without even going to the Greek/Hebrew/Aramaic.
Unfortunately, when someone adds "In the Greek it REALLY means 'xyz'", they get a fealing of completed action in whatever point they are trying to win.
While they can be genuine, when people go to the Greek/Hebrew/Aramaic to make their point I usually suspect their motive.
IMO
Having said that, reading the GNT this second time has made the Word more meaningful to me in English.
Brother Bob, I just knew there had to be something we agree on and here it is!
But I have found a Greek word-study useful from time to time, but like has been said, it is usually abused to make an argument seem indisputable.
Also, I agree that Greek words, like English words, can only be understood, after basic grammatical application, in their CONTEXT.
I often get angry with people that start quoting Greek words to prove their point because it strikes me as dishonesty - an attempt to put up a smoke scrren to divert the discussion away from the point being made.