Yesterday’s Parsha discusses the punishment for not observing the Mitzvot. Rashi points out that the Pasuk, אם בחוקותי תמאסו, if you despise my statutes, indicates seven stages of turning against Hashem.
The stages of deterioration are as follows: It begins with לא למד, he does not study Torah. This is followed by לא עשה, not observing the Mitzvot. The next stage is מואס באחרים העושים, despises others who do observe. He then is שונא את החכמים, hates the Rabbis. After this, מונע את האחרים, prevents others from observing. This leads to כופר במצוות, denying the Mitzvot. And the final stage is כופר בעיקר, he denies the basic principles of Judaism.
It is understandable how this is a clear indication of turning against Hashem. Such actions will be met with severe punishment.