Earlier this week Pope Francis argued the church should display grace and be more open to baptizing all who come seeking after it, regardless of their parents' practices, for example. While I disagree with the way the Catholic church practices baptism (and a lot of other things!), I would certainly applaud the driving point the Pope is making - the church should be open to receiving all who come desiring to place their faith in Christ.
But, I would certainly want to limit what I mean by all to all . . . humans. To illustrate his openness, the Pope said he would reach beyond humanity and extend baptism to green martians, "green men, with a long nose and big ears, like children draw," and "If tomorrow, for example, an expedition of Martians arrives and some of them come to us ... and if one of them says: 'Me, I want to be baptised!', what would happen? . . . Who are we to close doors?”
I understand the Pope was simply illustrating his point and not laying down church doctrine for ET. I can only imagine a Green Lantern or Jedi style meeting of cardinals from a plethora of human-like species. After all, Yoda would look ridiculous in a mitre.
An illustration though it may have been, it misses the whole point of what God did when he sent Jesus to become a man and take on human flesh. Hebrews 2:14-18 makes clear that he "had to be made like his brothers in every respect." Jesus didn't take on humanoid flesh - which could potentially include anything with two legs, two arms, opposable thumbs, and the ability to fly a spacecraft. No, he took on human flesh. The same humanity that Genesis 1:27 tells us was created in the image of God.
So, to answer the Pope's question, "Who are we to close the doors?" We're Christians, who have been given the truth of God's Word and have an obligation to order our practices by it. We don't get to make it up as we go long so that we sound more compassionate.
So, just to be clear, aliens can visit our church anytime. They can come to potluck and we'll fellowship with them if they want to hang out. But, the Bible doesn't allow us to offer them salvation through the person and work of Jesus Christ. And, therefore, we can't baptize them either. Plus, remember what happened when they spilled water on Gizmo - I mean, you never know!
Praise God that Jesus took on human flesh that we might have life. That's more precious than you or I can ever imagine!