John Calvin Commentary Luke 12:50

"But I have a baptism to be baptized with; and how am I straitened till it be accomplished!" — Luke 12:50 (ASV)

But I have a baptism to be baptized with. By these words our Lord asserts that there remains nothing but his last act, that by his death he may consecrate the renovation of the world. For since the shaking which he mentioned was appalling, and since that conflagration of the human race was terrifying, he is about to show that the first-fruits must be offered in his own person, after which the disciples should not be displeased at feeling some portion of it.

He compares death—as in other passages—to baptism, (Romans 6:4), because the children of God, after having been immersed for a time by the death of the body, shortly afterwards rise again to life, so that death is nothing else than a passage through the midst of the waters.

He says that he is sorely pressed until that baptism has been accomplished, so that he may encourage every one of us, by his example, both to bear the cross and to prefer death. Not that anyone can have a natural preference for death, or for any reduction of present happiness, but because, when we contemplate on the further bank the glory, and the blessed and immortal rest of heaven, we not only suffer death with patience, but are even carried forward by eager desire where faith and hope lead us.