Sadly, the church has become lax in discpilining it's own. A group of Baptist pastors needs to go to Mr. Phelps and bring correction to him. If that doesn't work, they need to go to the Baptist association, and if that fails, they need to go public and the Baptist association needs to toss him out.
For a Baptist, who have been great at developing systematic theology, Phelps doesn't seem to grasp much of the gospel's point, which is to love the lost. God doesn't hate gays any more than he hates murderers or gossips or adulterers or liars or theives, which is to say that he doesn't hate them at all. He may hate their sin, but last I heard, gay sex was listed right there with drunkenness, slander, coveting, lying, killing, fornicating, selfishness, and anything else we know to be wrong.
The Lord has told us that judgment first will come to the House of God. Fred needs to be told that as an ambassador for Christ, his representation of Christ by presenting the Gospel as bad news is not likely to be viewed by God as something to be put up with for much longer. Pride goeth before a fall, as it says....
I don't think he's part of any Baptist association. "Baptist" is like "Catholic"; it's not a trademark. Anyone can call themselves a "Baptist pastor".
Phelps is a stooge in the service of, and probably also in the pay of, the loony left. His purpose is to make serious Christians look like freaks in front of the media. The "church" he really belongs to is the church of the far left.
When Phelps' gang protests, they hold gaudy signs designed to offend, walk around, and maybe chant some slogans. They don't sing hymns. They don't pray together. Doesn't sound like any Christian protest I've ever been involved with.