The Bible tells us that God created the earth to inhabit life:
“For this is what the Lord says—he who created the heavens, he is God; he who fashioned and made the earth, he founded it; he did not create it to be empty, but formed it to be inhabited —he says: “I am the Lord, and there is no other.”
– Isaiah 45:18
The earth is certainly fulfilling that purpose; our planet is teeming with life – sea creatures, flying creatures, creatures that walk on the earth, and, of course, man. This scripture also tells us that God does not create things ‘simply for nothing,’ so we can safely assume that while some planets are formed for other purposes, there are many planets that were formed to be inhabited like ours, and likely are currently inhabited by various forms of life.
When we look into our universe, we see billions of planets, all spherical like our earth. Thus, we conclude that it is God’s purpose that His various living creations would be domiciled on spherical planets like earth. We cannot imagine that the angels must perpetually fly. The Father is merciful enough to provide roosts for the birds. (Matthew 8:20) Surely, angels, too, must have planets that were formed for their habitation.
But earth is not the only home for mankind. Jesus told us:
“My Father’s house has many rooms; if that were not so, would I have told you that I am going there to prepare a place for you? And if I go and prepare a place for you, I will come back and take you to be with me that you also may be where I am.”
– John 14:2-3