What does this mean "machine guns looked like praying mantises to me"?

In this excerpt from "dover beach" by matthew arnold, which two lines or sets of lines suggest that the speaker has undergone a loss of faith? the sea of faith was once, too, at the full, and round earth's shore lay like the folds of a bright girdle furled. but now i only hear its melancholy, long, withdrawing roar, retreating, to the breath of the night-wind, down the vast edges drear and naked shingles of the world. ah, love, let us be true to one another! for the world, which seems to lie before us like a land of dreams, so various, so beautiful, so new, hath really neither joy, nor love, nor light, nor certitude, nor peace, nor for pain; and we are here as on a darkling plain swept with confused alarms of struggle and flight, where ignorant armies clash by night.

What is one way to appeal to ethos?

You suspect that this article has left out some facts that might lead the reader to believe that someone else made the star-spangled banner. what is the best way to verify this? by consulting a variety of sources by disregarding the article entirely by writing a letter to the editor of the publication that printed the article by reading various historical accounts by verifying the opinions