with greater vigor

Joseph Fielding Smith: We are informed that these [terrestrial individuals], although they may not be members of the Church, who are entitled to the blessings of the terrestrial kingdom, will be spared. Therefore, there will be millions of people on the earth during the millennium who have not received the gospel. Missionary work will continue with greater vigor and power than at any other time. This work must go on until all who are on the earth are either converted or are taken away by death. (Answers to Gospel Questions, Vol.2, p.200).