Take the Red Line Outbound and get off at Central Square. When you reach the street level, turn onto Prospect Street and walk several blocks until you reach Broadway. Turn left. Walk until you reach the Broadway Bicycle Shop and then turn right onto Antrim St. The church is about halfway down the street on your left.
Take the Massachusetts Turnpike (I-90) East to exit 18 (Alston/Cambridge) or West to exit 20 (Brighton/Cambridge). Exit and after the tollbooth, bear right towards Cambridge. Go through the light, over the Charles River and continue on River Street. After you cross Massachusetts Avenue, at Central Square, the street you have been following becomes Prospect Street. Continue on Prospect Street to the third traffic light after Central Square. At this light, turn left onto Broadway. Go through one more light and look for a parking spot. Antrim Street will be the next street on your right but it is a one way street in the opposite direction. You could turn right at the following street (Fayette St.) and then right and right again to get onto Antrim, but it's easier to park on Broadway and then walk up Antrim St. to the church.