The Omen movie

Robert and Katherine Thorn seem to have it all. He is the US Ambassador to Italy and they want for nothing in their lives, except one thing: they do not have children. When Katharine has a stillborn child, Robert is approached by a priest at the hospital who suggest that he take a healthy newborn whose mother has just died in childbirth. Without telling his wife he agrees to to so but after relocating to London, strange events - and the ominous warnings of a priest - lead him to believe that the child he took from that Italian hospital is evil incarnate.