Some say understanding Jewish apocalypticism and the historical context of the NT is a form of gnosticism-- some special knowledge that only the intellectually elite can attain.

It's exactly the opposite.

Knowing what Jews actually believed about things like the day of judgment, the resurrection of the dead, the kingdom of God, and Gehenna delivers us from the theological plague of "spiritualizing" everything (which is the real and original gnosticism).

It actually allows us to read the NT in a plain, common sense manner. - John P. Harrigan