[zorg]

Alas, I can't help you with Latin grammar, never having learned Latin. However, I can throw unfiltered thoughts at you.

A possible workaround comes to mind: you could settle for a grammatically less complex, more poetic motto, which still catches the same meaning :) Something like "From Death we guard", or "Always we serve", or "In our hands" (...the fate of humanity rests), or "Duty from Conscience". Something like that.

I think if a basically ideologically motivated group were to pick a motto, they'd go for something catchy, impressive-sounding; rather than a precise description of what they want or do.

Fluctuat nec mergitur sounds better than Even though things might be difficult at times, we're still determined to carry on.