By the looks of it is fairly new.
Edit: Seems like they're associated with Damien Ba'al http://atheisticsatanism.com/curiosity/
Hey look at it this way, It appears to be a collection of links of Atheistic Satanic resources. Of which your site is the first listed. Spin that as the most relevant.
Following SIN is; TST, UK Church of Rational Satanism, MCoS, First Satanic Church, Greater church of Lucifer, CoS, and Sect of The Horned God, in that order.