What does "raise a peep out of anything that isn't us?" mean?

A peep is the tiniest of sounds that the smallest birds make. If you fail to raise a peep, you aren't making a sound. So, it would appear, barring more info, that for all the messages or work these people have done, it hasn't raised any noise or interest except among themselves. In other words, they're preaching to the choir and nobody else is listening.

What have we been doing all these centruies but trying to call God back TO the mountan, or, failing that, raise a peep out of anything that isn't us?

They are trying to get God or aliens (anything that isn't us) to speak to them, but they haven't been able to hear a sound.

Joe(Hello, hello! ..... )Nation

In biblical times, prophets went "to the mountaintop" to speak with God.

Mc(or so we are told)Tag