dwelleth = dwells "eth" is the old English 3rd person singular ending of verbs. It is not used in modern English. You'll see a lot of it in some bibles though.

Yes, it is. It is from the Bible (King James Bible), Psalm 91. Dwelleth is a form that it is not longer used. It comes from Middle and Old English. You sometimes here these forms in set expressions or rhymes: Thirty days hath September, April June and November .... Other remnants of Old and Middle English that you sometimes hear or see are: Ye olde Coffee / Tea Shoppe = the old tea or coffee shop O ye of little faith = o you ... Many of these phrases come from the King James translation of the Bible. Also you might see thou / thee / ye especially when you read older literature. Thou = you singular nominative; thee = you singular accusative; ye = plural nominative Also what is a little strange is the use of shall. Nowadays we tend to use will in most cases, with one or two important exceptions: Let's go, shall we? Shall I / we help them? As far as I know, will was used with the second and third persons [you, he,she it] when no emphasis was required and shall was used with the first person [I, we] when no emphasis was required. However, when it was necessary to be emphatic, roles were reversed: I / we will, but you, he, she, they shall. What probably happened is that 'will' came to be used in most cases with all persons, even when emphasis was not required. However, as I mentioned, some situations do require the use of shall in the first person, and not will. Back to the quotation, 'shall' is being used here for emphasis, but nowadays the word 'will' would be used. QED: He who dwells in the shelter of the Most High will abide in the shadow of the Almighty. [English Standard Version Bible] This is the same Psalm as the one you quoted, 'translated' into Modern English.