(You) let us (you and me) (to) pray about it.
(You) implied subject of let.
let is the main verb.
us is the direct object of the verb
you and me compound direct object explaining *us*
(to) pray is an infinitive phrase acting like an adverb and modifying the verb let
about is an adverb modifying pray; alternately, it could function as a preposition, but I prefer adverb since that enhances the way we pray ;-)
it is the direct object of pray