What is the purpose of contrasting the scene of the Jewish wedding with the scene of Schindler's birthday party and the scene of Goeth beating Helen?

The inter-cutting of the scenes of Goeth beating Helen and the Jewish wedding serves to compare the triumph of human spirit and the breaking of it. Instead of simply showing the wedding straight through, Spielberg inserts clips of Helen's beating to remind the viewers how remarkable a wedding is at a time that is so horrible.