Answer

There seems to be a sense of accusation or questioning ‘what hinders? Are you beam-blind, yet to a fault in a neighbour deft-handed? Are you that liar and, cast by conscience out, spendsaviour salt’?

This could be addressed to god, it could be read as the thoughts of the same speaker in the octet (the opening eight lines), who is addressing God in a very bitter voice. In this case the speaker would be seeking God to mend the speaker's fading faith, where the "indoors" would be his own internal self. In the last 3 lines the speaker could be addressing God in angered tones with brash sounding consonants, emphasising his unhappiness such as ‘beam blind’ which has harsh, angry alliteration.