Friedrich and Søren attack the institution, not the religion itself... not all that familiar with Sartre though.
The religion that I feel most connected to would most likely be the Old Religon - Wicca (Eclectic)... probably the friendliest religion ever (and if christianity ever finds its true path it'll resemble wicca). The Wiccan rede: "An Ye Harm None, Do What Ye Will"
In case if you're interested: http://www.religioustolerance.org/wic_faq.htm (there's also a small part where Wicca and Christianity relationship is explained)
"Wicca" was invented in the 1920s by a homely guy named Gardner so he could meet chicks.
. . . not a really sound basis for a belief system, IMHO.