Sanhedrin 90 - Share in the World to Come
All Israel has a share in the world to come . However, the following don't have this share: one who says that there is no reference to the Resurrection of the Dead in the Torah; one who says that the Torah is not from Heaven; and one who disparages Torah scholars, which leads him to deny the existence of God. Other sources also enumerate multiple other transgressions, which, if performed habitually, lead one to lose his share in the World to Come, bu they can be derived from the list above.
Rabban Gamliel gave this source for the Resurrection of the Dead in the Torah: God saying to Moses, " Behold, you will lie with your forefathers and rise ..."
Art: Claudio Francesco Beaumont - The Resurrection of the dead