I think we need to be careful with the way we view people such as this. Whether it's religious extremism or racial or any other type. At the end of the day they are sinners, just like everyone else here. Their sins may be more public than ours, but because we hide our sins doesn't make us better or less sinful than this group.
While i am absolutely 100% against the message they teach, we need to stop and ask ourselves what if God had the mentality we have. Paul was a hateful religious nut who did more than celebrate death, but went on a crusade to kill and murder every Christian he could find. If the attitude that is reflected in this post (and i'm not just speaking to Scrpitureplz, but anyone who would share a similar sentiment) were aimed at Paul (Saul) then where would we be today?
People like this, that do evil, even in the name of God, are just lost sinners with no guidance. Same as we all were at some point in our lives. While they may be horribly misguided, there is also a zealousness and boldness they have that often lacks in the actual church. While the church is sitting online, behind their keyboards, talking crap about other people and how horrible they are, these people are out speaking boldly, and in public, about what they think God is about and willing to face the persecution that could follow.
Imagine if we took their active, bold spirit and mixed it with the truth of the real gospel, what kind of influence could be had. Instead of sitting in our chairs talking about what horrible people others are. Because without God's forgiveness you are just as equally sinful as the Westboro people. You are no less deserving of hell than they are. None of us are any better without God's gift of salvation.
