Cozy but Quick Sushi place Trinity Church: Broadway at Wall Street
Unfortunately there isn't any good Japanese restaurants in downtown financial district, so if you don't mind a stop I will suggest heading to East Village for your dinner on your way to the church.
You can take the 4, 5 train to 14th street, switch to the opposite for 6, and stop at Astor Place. Then you can head down to Kanoyama on 2nd Ave and 11th Street for some delicious sushi. It is a small restaurant but the food there is fresh and delicious. Their cooked food is also fantastic! Unless you are sitting at the sushi bar for omakase, the regular sushi platter on the menu should be quick and reasonable priced. After the meal you can head back to the 6 train to downtown. Switch back to 4,5 at Brooklyn Bridge platform and it goes all the way to Wall Street.
If you get out at the right exit, Trinity Church will be right outside of the subway entrance.