The mormon belief of being able to preach and convert after death stems from new testament teachings in Peter that Christ preached to those in "prison". And wh

The mormon belief of being able to preach and convert after death stems from new testament teachings in Peter that Christ preached to those in "prison". And while many Mormons take the necessity of baptism (even if after death) very literally, it is important to understand that they also believe that anyone who missed the chance to accept a posthumous baptism, will get that chance during the millennium of Christ's reign on earth, pre-judgement day. All of that is to say, Mormons aren't frantically searching their genealogy to baptise everyone for fear their ancestors will burn in hell. There is a belief that seeking out and understanding your geneology and then setting aside time to go to the temple is beneficial to ones spirituality and well being.