One thing to remember is to separate the sin from the sinner.
I would say that what the JWs teach that is in error (and there are alot of errors in what the JWs teach) is evil in that it makes God out to be less than what He truly is AND they make it appear that God has given us less than He has truly given us. So, yes, in many respects the teachings of the JWs are evil.
Also, the actions of certain JWs can be evil just like our own actions can be evil. Now, in the JWs’ case, there are certain actions encouraged by the JW religion that are evil such as shunning and pressuring individuals through the threat of shunning into certain actions such as refusing Blood Transfusions.
Now, in many cases the people among the JWs who teach this error and behave in ways encouraged by the JWs, do this in ignorance. This does not make the actions any less evil but it does perhaps lessen their own responsibility toward doing these evil acts since they may not know any better. Those who participate in these evil acts but know better are the ones that are in real trouble. Since only God can make these judgments, I think we would be better off giving people the benefit of the doubt (just as we hope people will give us the benefit of the doubt when we screw up).
And, we should by giving our JW friends the benefit of the doubt in these areas, reach out to them with the truths of the Catholic Church in a spirit of love and charity. By doing this we will collaborate with God in saving many of our lost brothers and sisters from this evil and lead tons of lost souls to Christ.
Jeff Schwehm
www.catholicxjw.com