[If man could sin in the pre-existence, then how does such a concept reconcile with the scripture that says 'no unclean thing can dwell with God'? (1 Nephi 10:21)]

A careful reading of this and related scriptures will reveal that the word "dwell" as used in this context refers to a permanent or eternal condition that exists after men are brought "before the judgement seat of God" (1 Nephi 10:21; 3 Nephi 27:19; Mormon 7:7; D&C 76:62). Dwelling, in this sense, is a future condition.


Tad R. Callister, The Infinite Atonement. 2000. p. 77, 78