Many preachers have a go-to phrase that expresses their take on the ministry. You might even say it's their mission statement. For Saint Francis of Assisi, it was "Preach the Gospel at all times, if necessary using words." A former pastor of mine liked the phrase, "Where there is no vision, the people perish." The church I currently attend used the motto "Love Matters" when I first joined. They let you know what kind of person, what kind of congregation, they aspire to be.
Then, you have Fred Phelps. His motto ... well, it wasn't so much a motto as it was an answer to an interviewer's question. When asked about his approach, when asked what he felt about being so widely hated, he said, "Good. If I were not hated, what claim could I have on the ministry of the Gospel?"
That, I think, is the key thing you had to understand about Fred Phelps, and the key thing you had to understand about how to deal with him and his followers. He loved being hated. It was his measure of success. Back when supporting civil rights got you death threats, he was all about civil rights. If you ask how someone who was so right back in the '50s could be so wrong now, you ask the wrong question; the man simply enjoyed the opprobrium of his fellow citizen. Now, why he enjoyed it so is a fair question, but one that has now been rendered somewhat moot.
I never wasted a whole lot of time thinking about him, or his bloated distortion of Christianity. And I never wasted much time on hating him or his followers. Hate is the wrong response anyway, since that's what they crave. No, I'll tell you the proper way to treat them -- as they deserve.
You don't hate clowns. You point, and laugh at them.