From the south - Head north on Rte 3. At Exit 7 in NH, Rte 3 becomes the F.E.Everett Tpke (with no effort on your part. Just continue on the same highway). Leave the Everett Tpke at Exit 12 (50 cent toll for autos. E-Z Pass™ is accepted). Take a right at the traffic light at the end of the exit ramp. Take a right at the next traffic light as well. You should now be on Daniel Webster Highway (DWH) heading south. The chapel is at 590 DWH on the right, just beyond Tortilla Flats restaurant. If you see Shaw's supermarket on your right, you have gone a bit too far.
From the north - While this is not the most direct route, it is probably the least complicated. The above directions indicate exiting Everett Tpke at exit 12, but exit 12 is only a half interchange and does not have an exit heading south. The simplest thing to do is as follows: Head south on F.E.Everett Tpke and exit at Exit 11. Bear right and take a right at the traffic light. You should now be heading north toward another traffic light with the Tpke on your right. Take a right at that traffic light, proceed east under the Tpke and straight through the next traffic light just after the bridge. With TD Banknorth on your right, take a left at the next traffic light. You are now on Daniel Webster Highway (DWH) heading north (this is also Rte 3 if you are using your own map).Faith Church is on the left just beyond Shaw's at 590 DWH.
NOTE: Faith Episcopal Church is at 590 Daniel Webster Highway in Merrimack which is Rte. 3 on any reliable map. There are more direct routes from the north than indicated above, but some of the interchanges required to reach Rte 3 south (particularly in Manchester) can be complicated so the above method is probably one of the simplest. If you can navigate your way to Rte.3 south from the Manchester/Bedford area it would be more direct.