Settle down and abide. Take up His permanent abode, so that ye may be a habitation (κατοικητήριον) of God. See on Eph 2:22. The connection is with the preceding clause: “to be strengthened, etc., so that Christ may dwell, the latter words having at once a climactic and an explanatory force, and adding the idea of permanency to that of strengthening.
By faith (διὰ τῆς πίστεως)
Through your (the article) faith, as the medium of appropriating Christ. Faith opens the door and receives Him who knocks. Rev 3:20.