the jackdaw, the carrion vulture, the cormorant,

So, you people should stand firm [in the faith], with the belt of truth firmly buckled around you, and with the "flack jacket" of righteousness on your chest.

But, since we belong to the daytime [i.e., are enlightened], we should be sober. We should put on the "flack jacket" of faith and love, and for a helmet, the hope of being saved.