There are a lot of under-rated blogs in the blogosphere. The most under-rated blog by a long shot is Steve Hays' Triablogue, which Phil has always linked in the sidebar.
Now that Steve has a gang-blog working, it's almost impossible to read all the stuff they are producing and it is also almost impossible to beat it all. Today, due to the topics at-hand at TeamPyro, I'd refer you to Gene Bridges' fabulous recent post on assurance and the local church.
Don't mess with Gene. He doesn't play.
HT: Gummby (side-kick in training)