If only You would rend the heavens and come down, so that mountains would quake at Your presence,
Here, I. The petition is that God would appear wonderfully for them now, Isa 64:1, Isa 64:2. Their case was represented in the close of the foregoing chapter as very sad and very hard, and in this case it was time to cry, "Help, Lord; O that God would manifest his zeal and his strength!" They had prayed (Isa 63:15) that God would look down...
Commenting on Isaiah 64:1-5
O that thou wouldst rend the heavens, that thou wouldst come down,.... Before, the church prayed that the Lord would look down from heaven and behold, Isa 63:15, now that he would open the heavens, and descend from thence; not by change of place, for he fills heaven and earth with his presence; but by some visible display of his power, in destroying her enemies, and delivering her from them.
O that thou wouldest rend the heavens, that thou wouldest come down, that the mountains might flow down at thy presence, (a) The prophet continues his prayer, desiring God to declare his love toward his Church by miracles and mighty power, as he did in mount Sinai.