Religion closest to Judaism

[Jason]

In terms of personal observance, traditional Islam is more similar to traditional Judaism than is traditional Christianity. That said, liberal Christianity is more similar to liberal Judaism than it is to liberal Islam.

Is there such a thing as liberal Islam?

Yes, there is. The problem is that the moderate and liberal expressions of Islam have no voice in the institutions of Islamic thought. They are generally ignored and the people considered كُفَّار kuffar "infidels" or "unbelievers," much in the way that Reform Jews are nearly considered כּוֹפְרִים kofrim "infidels" by the Ultra-Orthodox.