The Prowler (1981)
The gazebo scene was filmed at Seaville United Methodist Church (Route 9 South in Seaville, NJ). The gazebo sits in the center of a small pond on the property, and you can see parts of the church itself in the background during the scene.
A large Victorian building (next to the Cape May Post Office on Washington St.), which was in disrepair at the time of filming, was used as the location for the climax of the film. Years later it was purchased, refinished, and now operates as the Southern Mansion bed & breakfast.