"But I have a baptism to undergo, and what constraint I am under ..." (Luke 12:50)

"But I have a baptism to undergo, and what constraint I am under until it is completed!" (Luke 12:50)

Is this translated correctly?

Unfortunately, this translation is dubious given the original Greek.

The Greek word βάπτισμα (baptisma) has been translated to "baptism" - which is interpreted to mean the process of formal initiation that includes being immersed in water.

But the most common meaning of this Greek word βάπτισμα actually means, according to the lexicon, "immersion, submersion - of calamities and afflictions with which one is quite overwhelmed."

Furthermore, the Greek word συνέχω (synechō) is here being translated to "this constraint" but actually means "to hold together" according to the lexicon.

As such, we can have a clearer understanding of Jesus' statement here. A more appropriate translation of his statement would relate to being immersed in a difficult situation, which would be kin to being challenged. Here is the translation of this verse from the Lost Gospels of Jesus:
"Yet I have a challenge to undergo, and I will press on until it is done." (Luke 12:50)

What is this challenge?

And what is Jesus keeping together?

Jesus is portraying that he has become immersed in a difficult situation and he is focused on keeping things together until he accomplishes his goals.

And what are his goals related to? They are related to doing the will of the Supreme Being:
"As long as it is day, we must do the works of Him who sent me. Night is coming, when no one can work." (John 9:4)
To do "the works of Him who sent me" means to be serving the Supreme Being. Jesus was God's loving servant, and his mission was defined by the Supreme Being.

And what were the primary "works" of Jesus? He traveled through the countryside teaching. Jesus was teaching others about the Supreme Being. 

He was sent to teach those who are serious about returning to their relationship with God about coming to know and love the Supreme Being.

We know Jesus was sent to teach by the Supreme Being because not only did he endeavor with great difficulty to travel around by foot and teach to people, but he specifically said he was teaching on behalf of the Supreme Being:
“My teaching is not my own. It comes from the One who sent me." (John 7:16)
Where was Jesus sent from? As Jesus himself admitted, he was sent down to the physical world from the spiritual realm:
"For I have come down from heaven not to do my will but to do the will of Him who sent me." (John 6:38)

Did Jesus descend from heaven into hell?

Actually, this physical world that we are living in - with its violence, hatred, wars, starvation, disease, and death - is hell. This is a place of suffering, where its citizens are primarily self-centered and prepared to hurt others in order to get what they want. And Jesus has descended into this hell in order to give us God's teachings.

This is the immersion Jesus is speaking of in Luke 12:50. He is not speaking of some kind of ceremonial baptism. In his service to the Supreme Being, Jesus immersed himself into this hellish physical world.

Why? Because the Supreme Being wants us to come home. God wants us to give up our self-centeredness and renew our innate loving service relationship with Him - and come home to Him. He wants us to return to our natural position and our spiritual identity as His loving servant - because this is the only way we will ever become fulfilled.

So the Supreme Being sent his beloved Jesus to save us. Jesus basically descended into hell in order to accomplish this purpose of teaching us and showing us about our true identity as spirit, not the physical body - and teaching us about our relationship with the Supreme Being.

It was a difficult assignment - wrought with danger and accompanied by Jesus' physical body being persecuted and murdered at the hands of those who were envious of his authority and power.

And as we can see from the scriptures, up to the very end of his physical lifetime, Jesus continued to focus upon his mission - allowing us to understand the importance of loving service to the Supreme Being.

Jesus prayed, as he knew he was to be arrested and persecuted in the coming hours - and certainly had the option of escaping into the night and avoiding arrest if he wanted to - that he continue to do what pleases his beloved Supreme Being:
Going a little farther, he fell with his face to the ground and prayed, “My Father, if it is possible, may this cup be taken from me. Yet not as I will, but as You will.” (Matt. 26:39)