The mishna that begins the current chapter talks about who has shares in the World to Come (Olam HaBa). We learn: all Israel have a share, except that the following have none: one who holds that resurrection of the dead (in the time of the messiah) is not biblical doctrine;1 one who holds that the torah was not divinely revealed, and an apikorus (here meaning a heretic; the word derives from Epicurean). R' Akiva adds: one who read uncanonical books; this might refer to Gnostic books or might refer to ascribing scriptural status to other books. R' Akiva also adds one who says a certain kind of magical charm, and Abba Saul adds one who pronounces the divine name as it is written. The mishna then goes on to single out seven individual people who have no share in the World to Come: the three kings Jeroboam, Ahab, and Manashe, and the four commoners Bilaam, Doeg, Ahitophel, and Gehazi. (90a)
The g'mara goes on for pages and pages from this mishna -- the next nine pages revolve around resurrection of the dead and the messiah. Today's daf, 95, is in the midst of that discussion, which is why I went back to the mishna rather than diving in there. I don't yet know the reasons for all seven people who are singled out.
1 A note in my translaton points out that the Sadducees and the Samaritans denied resurrection (and were relevant groups in mishnaic times).
(The last two Thursdays were holidays, hence the interruption in daf bits.)