The guy who created the "church" was Fred Phelps (he's dead): From what I remember about him, he was actually a pretty intelligent individual, and was somewhat of an athlete (boxing), who managed to secure an appointment to West Point. In the year between graduating HS and entering West Point (he graduated a year early for one reason or another), he had developed an interest in religion and never attended.
Though his initial beliefs did not appear too fanatical by the standards of the time, they became aggressive fairly fast, and had actually found himself in brawls. He would be described as a Five-Point Calvinist, who believed that most people were pre-destined by God to go to hell, and only a small elect would be destined to see the gates of Heaven. Of course, his narcissistic personality, would lead him to naturally believe he was one of these "elects".
At some point (probably in the 1950's), he was either drunk or high out his face and gunned down a dog that crossed onto his property (his property was not clearly marked) if I recall. The people who lost their dog sued him, tow which he defended himself and won; he then counter-sued. Realizing the power of the legal-system, he started launching lawsuits against anybody he could . The fact that he gunned down somebody's dog also angered some people who went to his church, who left.
He would eventually go to law school and, while he took up many civil-rights cases, he would prove to be a crooked lawyer prone to litigious suits and extortion (sue somebody, then tell them if they gave him some money up front, he'd drop the charges -- he even did this to his clients -- well former clients at least). Since he was a narcissistic bastard, he saw everything as revolving around him, and made his kids go to law-school, overriding their own desires and dreams in life to "defend the church", which in this case meant "adding manpower to support his lawsuits".
His civil-rights work would actually get him an award by the NAACP, but the thing was -- he was a racist: He basically felt that white people were the servants of God, and black people were the servants of white people -- servants of the servant. He defended them as a result to an extent, and probably also to look good (he seemed to fool the NAACP): To keep the status quo, he would often sue, but settle out of court, rather than push to verdict -- policy only changes when a verdict is passed.
It probably wouldn't be surprising that he was an abusive bastard: He threw his wife down the stairs once, dislocating her shoulder, and prevented her from seeking medical care; he beat the shit out of his kids countless times: Girls and boys got the leather strap at first, then the boys would later get the mattock handle (a mattock is a pick-axe, the handle is about twice the density of a baseball bat) causing all sorts of bruising, probably some bleeding, and bone-chipping. In one case, child protective services were called in as one of his kids had exhibited signs of shock in school -- remember, this was around 1968 -- you had to damned near kill your kid to get that to happen!
In addition to having an unsavory personality to begin with, he had substance abuse issues. At the very least, he would have an alcohol addiction prior to going to law-school. After this point, his addiction would grow to include uppers (amphetamine and methamphetamine) and downers (barbituates). Though he would kick the drug habit, detoxifying himself, and also going on a starvation diet, he would go from being tall and pudgy to bony thin.
Now anything that seems good for Fred Phelps almost always has a way of going bad, and it did: He became a health-nut; then proceeded to force his kids along for the ride. Being naturally athletic, he found he was quite adept at running considerable distances, and would eventually be able to run marathon distances -- something he forced his kids to do also. At first, the local media was actually quite impressed, and then rather dismayed when they found out they were being forced to do this, as it's not really healthy for people that are pre-pubescent (his kids ranged from pre-pubescent to teenagers). He also had plenty of time for all this as he had been suspended for practicing law due to his legal practices.
He would be suspended several times actually, and eventually disbarred in the state of Kansas. This also kept him out of Federal courts for awhile as well, though when he came back, him and his kids were involved and, by God he started right where he left off. His actions might very well have gotten more aggressive rather than less, and him and his children were basically on the verge of being disbarred. He agreed to a deal that would see him surrender his license, and his kids would keep theirs. While they figured this would be good because plea-bargains generally deny one the right to appeal and theoretically stopped him from practicing law.
It didn't stop his sons and daughters as, once their suspensions ran out, they were capable of going back to practice law. At about this point in time, he started a crusade in a Park (Gage Park) which was supposedly an area where homosexuality was commonly practiced. The protests we mostly know him for started at around this point, but he wasn't picketing the funerals of soldiers, he would picket the funerals of people who were either known to be homosexuals and/or those who had died of HIV/AIDS. The purpose of this was largely out of a way to make money.
- He filmed all his protests so anything done could be used as ammunition in a lawsuit
- He exploited periods of time where people were highly emotional, such as funerals, and likely to be easier goaded into acts of aggression
- Said acts of aggression would be used to file lawsuits when possible
His sadistic impulses probably would be gratified by doing this too. In other words, he actually wanted people to fight him. Though most people would find this prospect undesirable, he wasn't a particularly anxious man, he liked to fight and was also quite willing to take a few bruises and broken bones if it would allow his kids to sock 'em with a massive lawsuit.
Eventually either after 9/11 or after the invasion of Iraq he switched his campaign from "God Hates Fags" to "God Hates America" and started protesting the funerals of military personnel who died in war. His claim that because the country as a whole tolerated homosexuality, we are all evil -- at least that's his pretext -- the real reason was the same as before. Get angry and emotional people to attack him; then use that to set-up a lawsuit. I'm frankly amazed by the fact that he never got shot by some of these people.