Given how huge the universe is, why would God care only about Earth?
My immediate thought is “I don’t know”, followed by “Do I really have to know?”. It’s important to be very precise on what exactly the ‘objection’ here is.
1) Are we suggesting that God should have made many other planets with life, perhaps life similar to what we have on Earth?
But this is a strange ‘demand’, isn’t it? Why must a Creator create similar Earth-like planets without which He’s deemed less of a Creator?
Note that this assumes there ARE NO other planets with living creatures. But if there are then the issue morphs into, “What about those other creatures? Do they need a Saviour too, etc.? (To which my immediate speculative question would be: Whether or not they do, why should that affect our faith, the Bible, etc.? If there happens to be another form of life a billion billion light-years away, how does that change anything about the Christian faith? Is there anything in the Bible which hangs on there NOT being other alien life-forms?”
2) Are we suggesting that Earth is too small to warrant God’s attention?
But since when does size matter when it comes to significance? How much ‘bigger’ should Earth be in order to merit God’s love? Also, by this logic, should we love bigger people or larger communities more?
3) Maybe then the question is what is so special about Earth such that God has to pay it special attention?
If we’re focus on how God bestows favor, then Biblically speaking, there is usually nothing ‘special’ about anything God has chosen to bless or set apart. Two representative verses:
Deut 7:7, “The Lord did not set his affection on you and choose you because you were more numerousthan other peoples, for you were the fewest of all peoples. But it was because the Lord loved you…”
Romans 9:15–16, “God said to Moses, ‘I will show kindness to anyone to whom I want to show kindness, and I will show mercy to anyone to whom I want to show mercy.’ So God will choose the one to whom he decides to show mercy; his choice does not depend on what people want or try to do.”
Based on these verses, a quick answer to a question about how God chooses (a special people, a special planet, etc.) is that it’s entirely up to Him. This is at least one place where I think bringing up the strong idea of ‘divine sovereignty’ is helpful without causing hiccups to God’s character.
Unless some moral failure can be demonstrated, it’s up to God to choose to populate and save whatever planet He wants to.
Note, too, that this question (if phrased as an objection to the Christian faith) can easily regress into an endless cycle i.e. if God has put humans on Earth and Mars, then people could ask why only these two planets? If God put humans on a hundred or a thousand planets, then we could also object about the other planets.
Even if God put beings on EVERY planet, an objector could ask, well, why didn’t God leave some planets empty?