All Bible translators add indefinite articles ( a, an ) in there rendering of scriptures. The way it is translated agrees with the context of the scripture. Jesus being a Mighty God does not demean him or lower his statis or role in any way.
Agapa please don't buy into their pseudo scholarship. As a matter of fact john placed the words in such a way to emphasize the fact that there is no article there. If you do not believe me please go to your local university with your interlinear new testament find an atheist(non biased) student of classical greek and ask him to give you a literal(word by word) translation.I am from Greece and I took ancient greek and koine greek courses in high school and college. The watchtower has violated all sort of greek grammar and syntax rules in order to get the new testament to agree to their theology and that is one of their more horrific examples.