If a poem's called "Easter Wings," it's no surprise that religion is a big player. But religion is a huge subject, folks, and Herbert plays with our expectations and takes us in some unexpected directions. For instance, you might assume that the poem would actually be about Easter: Christ's death, resurrection, and appropriate Christian rejoicing. We do get some of the rejoicing, but the speaker sidesteps the main event, first taking us back way before the crucifixion, to focus on Adam and the fall, then way after, to tell us about himself in 1633. That means that the poem is less about Easter itself and more about the origins and repercussions of Easter: why Christ's victories, so to speak, were and continue to be necessary in the Christian faith.
Adam started it, but according to our speaker, every Christian continues sinning until they can "rise" with Christ and obtain forgiveness.
"Easter Wings" paints so grim a picture of human life that happiness can only be found in religious devotion. Which is precisely Herbert's point.