Exit Manhattan (preferably via Lincoln Tunnel or George Washington Bridge) 
onto New Jersey Turnpike SOUTH towards Trenton/Newark Airport.
Continue on Turnpike/I-95 SOUTH. (This is a toll road)
Turnpike will end - continue on I-95 SOUTH.
Cross over Delaware Memorial Bridge.
Continue on I-95 SOUTH towards Baltimore on the Delaware Turnpike.
Take the Fort McHenry Tunnel and continue on I-95 South.
Take I-495 WEST exit, exit number 27, towards College Park/Silver Spring.
This is the Capital Beltway (I-495)
Take the MD-185/CONNECTICUT AVE, exit 33, SOUTH towards Kensington/Chevy Chase.
Keep left in the fork in the ramp.
Turn left onto Connecticut Avenue.
When reach roundabout, go halfway around, and continue straight on Connecticut.
Turn left onto Porter St.  
(There will be  an Exxon gas station in front of you on your left)
Turn left onto Quebec St.  
Synagogue is on your right.

Directions from North Carolina:

Take I-85 North to I-95 North.
Take I-495 North/West to Bethesda.
Take MD-185/CONNECTICUT AVE exit towards KENSINGTON/CHEVY CHASE.
Keep right on the ramp.
Turn right onto Connecticut Avenue.
When reach roundabout, go halfway around, and continue straight on Connecticut.
Turn left onto Porter St.
Turn left onto Quebec St.  
Synagogue is on your right.