I'm surprised no one has quoted (that I've seen) these passages, which seem to advocate working alongside non-believers:
Luke 16:9:
And I say to you: Make to yourselves friends of the mammon of iniquity, that when you shall fail, they may receive you into everlasting dwellings.
Matthew 5:25:
Agree with thy adversary quickly, whilst thou art in the way with him…
This is a very good collection of quotes on how Catholics must deal with non-Catholics:
The Church's Constant Teaching on our dealings with Non-Catholics