What the heck does the phrase 'It stinks to high Heaven.' mean?

There is the first Heaven which is the sky. The second Heaven , the Sun and Moon and the third Heaven where The Most High sits. In our time the sins of man are so great they have reached the highest Heaven.

It's suspiciously corrupt. You smell a rat (very badly). 

Since gas rises, it means it skipped right past low-Heaven and went straight up to high-Heaven.
May the gas be with you. This post was edited by Merlin at July 4, 2018 8:30 AM MDT

it really really stinks