The northwest arete is the easiest route on Church Dome, and perhaps the most popular ascent option. The first ascent was made by Fred Beckey, Reed Cundiff, and Leland Davis in 1972. The arete looks steep and frankly quite intimidating from a distance, but abundant holds make the climbing surprisingly moderate. This is a short but excellent climb.
From the trailhead, head north towards Church Dome. If you're very good, you might be able to follow the trail up towards the saddle between Church Dome and Black Mountain. More likely, you'll lose it when it fades into nothingness, give up, and just head north via easy cross-country travel towards the peak. The highpoint is located towards the northwest end of the pinnacles.
From the base of the NW Arete, the route ascends in 1-2 pitches to a large platform at the base of the 5.7 summit block. (It may be preferable to climb the arete in two pitches to avoid rope drag).
(30m, 5.5): Head up on near-vertical rock with amazing holds--flakes, horns, and knobs galore. It may be best to belay just below the mildly annoying bush/tree encountered on route; there is a nice ledge here, and few opportunities for pro past this point.
(20m, class 3-4): Once past the aforementioned bush, the angle decreases dramatically and the arete becomes an easy scramble.
(12ft boulder problem, 5.7): This is the crux of the route, an unprotectable 5.7 boulder problem. Climb the NW side of the block on small edges.
5.7 summit block
To descend, rappel the route. There is a rappel bolt conveniently located on the summit block. Make a short rappel to the platform, and then make a 20m rappel from a prominent horn to another horn located just above the technical portion on the arete. A final rappel down the west side of the arete will get you down to the ground. (There is also an intermediate rap station part-way up the first pitch if you need it).
Be careful that the rope doesn't snag on any of the numerous flakes and horns.
A single 50m rope is adequate. A few medium cams suffice (#.5-#1 Camalots are most useful).