My answer to such a statement would be that if God exists, he certainly expects me to use what reasoning power I was blessed with to determine the best way to live my life. I would think he wouldn't want me to blindly follow others, but to do the hard work necessary to determine what organization, if any, is doing his will.
Having done this hard work and thoroughly investigated the WTBTS, and found that they lied about their history, beliefs and practices, honesty compelled me to sever my association with it. It was a very humbling experience to admit that everything I believed in was a lie, but that is my belief and I can do nothing less than follow my conscience, however hard that is.
If that makes me prideful in the eyes of others, then that is regrettable, but if they would condemn me without doing the hard work I did to determine the truth, then they are the prideful ones, not I, as they have blindly accepted an elaborate lie as the truth and then condemned for not doing the same.