The Leftovers had more of an "implicit" or inferred religious/supernatural bent to it in that 10-15% of the world's population just disappears and many people worldwide, politicians, religious leaders, various types of people all across the socio-economic spectrum sort of assume that it's The Rapture and that the next seven years are part of the Tribulation Period/End of the World, antiChrist vs. Second Coming of Christ Armageddon prophesied in Revelations. Some religious leaders, like Christopher Eccleston's character, dispute that the Rapture even occured at all, because according to his research, a good percentage of those "Disappeared" werent exactly morally-uprighteous, law-abiding, ethical people "worthy" in his view of being Raptured.
(Warning to those who haven't watched the end of The Leftovers: Season 3 TV series: Spoilers Ahead): We find out by the end of Season 3 that the Rapture didnt really happen and it was more of a inter-dimensional multi-verse screw-up (or Nora just outright lied about going to the other parallel world in the finale. The Tribulation Period nor the AntiChrist arrived nor did the Second Coming of Christ. But the Leftovers did present more of an overt religious, mystical overtones then Lost did at the beginning as opposed to introducing these themes in later seasons.