He was part of several councils within the Western church, as well as councils between the Eastern and Western church. Meeting Byzantine scholars spurred on his own musings.
He wrote several books that were widely read. Though he was never convicted of heresy, some of his beliefs bordered on Pantheism (the belief that God merged into the universe and is no longer a separate entity).
As Bishop of Brixen he wanted to reform the church, which led to clashes with the political authorities, as well as leading Pope Nicholas to revoke some of his changes. Archduke Sigismund of Austria who imprisoned him in 1460 due to some of those clashes. Which in turn led to the Duke being imprisoned, von Kues never returned to his bishopic.
Below is the Cusanus Coat of Arms (source)
von Kues was a man with a bright mind who was interested in a great many things, he started a winery, a natural scientist, interested in math and more.
In regards to von Kues and his trying to undertand God. He weaves his philosophy among several disciplines so it's hard to pin down well. He tried to explain it in his book "On Learned Ignorance" . He explained that God came before everything.... even before the very possibility of something existing. But since our reasoning can't make sense of that "Whatever I know is not God and whatever I can think of is not God". God should be described at the "not-other" as it is the best way to describe something that comes before everything else even if our thoughts can't conceive of such a thing happening.
To see a monument erected in his honour, check out this site.
Monument. coat of arms. Stanford Encyclopedia. Wiki. Cusanus Portal.