The Tanah [Mishnaic teacher] opens with "All Israel have a share in the World to Come" and then elaborates, concerning those who do not have a share in the World to Come, as follows: "One who says that resurrection of the dead is not from the Torah, [one who says that] that the Torah is not from Heaven, and one who denigrates the Torah. Rabbi Akiva says: Also one who reads outside books, and one who whispers [an incantation] over a wound, saying, (Exodus 15:26) 'I will not bring upon you any of the diseases that I brought upon the Egyptians for I the Lord am your healer' Abba Shaul says, also one who utters the Divine Name as it is spelled." End of quote. This, however, presents a question: Didn't the Tanah include all Jews who have a share in the World to Come, and then clarify in detail those who do not? If so, why did the Tanah include all Jews among those that have a share in the World to Come and then subtract those who do not? The Tanah should have started with those who have a share, and then taught about those who do not.
First solution: We are to understand that when there is unity in the nation, then "all Israel" have a share. All Israel the [Hebrew] acronym of 'all' = Cohen-Levite). When each one performs his role, Cohanim in their ritual, Levites at the duchan [the Temple platform from which the nation was blessed], and Israel maintain their prestige and when there is no superfluous strife or argument that cause divisiveness in the nation; when "all Israel" become unified as one, they all have a share in the World to Come.