Gerhard and Walther

Fourthly, something like this also appears to point to the fact that with the Baptism of Christ heaven has opened itself (Matt 3:16; Mark 1:10; Lk 3:21); for by this is shown that also in our Baptism, by which we are embodied with Christ, heaven is opened to us; and we are received as heirs of eternal life.—Johann Gerhard, Schola Pietatis I:91

Even if Christ had never spoken these word [the Great Commission], the Church would still be obligated to spread the Gospel throughout the world. Doesn’t each Christian have an eternal debt of love toward God? How, then, can he say that he loves God if he is able to look on peacefully as the enemy of God, Satan, holds in his snares millions of people who were created for fellowship with God?—C. F. W. Walther, God Grant It!, p. 101.