By the T (Green line):

D line: Get off at the Brookline Hills stop. Take a right onto Tappan St., then an immediate left onto Cypress St. Walk about five minutes to the intersection with Washington Street and take a left. The Church is the second building on your left.
C line: Get off at Washington Square and walk southeast about 20 minutes along Washington Street. The church is street number 416 and on the right side of the street.

Parking:

Parking in metered spots on Brookline streets is free on Sundays.  There are spots all along Washington Street and Cypress Street near the building.  Parking in the CVS parking lot is not recommended, there is the risk of being towed.