Hmm, Am I Allowed to Do This?

Usually, if I plan to critique a major authority, I try to do so using other major authorities. Yet, in my ongoing project concerning God's simplicity, I found I fired at several of Alvin Plantinga's (only the greatest living Reformed philosopher) objections to the doctrine using just my own reason. I wonder if I really should dare to challenge Plantinga so directly? My object initially was certainly anything but clashing with Plantinga.

Of course, I do use the reasoning of Thomas Aquinas, Karl Barth and C. S. Lewis in doing so — at least indirectly — so maybe I'm OK.