The man pushing Rose down in the water
After the ship sinks and Rose is separated from Jack, she swims through other helpless passengers. The man who held onto Rose before being punched off by Jack - was he the priest who, moments earlier, was helping passengers find some peace with their oncoming demise?
If yes, it is quite shocking - that a man whose occupation requires him to put others before him would cling to a 17 year old girl for life.