As a Christian, your focus should be on God and Jesus, not on earth. BUT you should appreciate all God has done! One of the things God has done is given us this wonderful earth to live on. If you look around, you see everything God has made and how wonderful and intricate everything is here on earth. This could not come from a big bang or evolution. Everything is so detailed that it had to come from an intelligent being- God. Just as when there is a painting there must have been a painter and there is a poem, there must have been a poet, etc., there is a creation so there must have been a Creator. So by appreciating earth, you are appreciating what God has made. It's okay to appreciate the earth, as long as you're not worshipping it or putting it above God. It's fine as long as you're focusing on how God made it and how awesome He is.