I was speaking to a colleague at work who was asking me about aliens. Do I believe there could be alien life on another planet? Given that our sun is one star in 100billion others in the Milky Way and that the Milky Way is one of countless billions of other galaxies surely there must be life on other planets. How could there not be? There are billions and trillions of possibilities. I've been thinking about it since then.
This is an important question when it comes to the bible. The bible says that we are special. In Genesis Ch. 1 we are told that human beings have been created in the image of God. We are the only beings in all of creation, the whole universe, of which this is true according to the bible. God created us in order to have a relationship with him, to worship and enjoy him forever. So the question of alien life is a challenge to the bible. If there are other forms of intelligent life that exist, then surely we are not that special. Who is right then? God’s word or the idea that surely there must be alien life in these billions of other worlds.
On the surface it seems like a solid scientific argument, 10,000,000,000,000,000,000,000 or 1*10^23 chances of there being another planet like ours. Surely one of these planets must have life. But this is just the surface of the argument. We have to look deeper. When we look at the physics and dig into figures not only do I think there is no alien life at all but actually we as human beings shouldn't really exist either.
Scientists used to talk about the Goldilocks zone. This means that if the earth was an inch closer to the sun or an inch further away than planet earth couldn't support life at all and this is true. But from what we've learned about the Big Bang, cosmology and DNA over the last 50 years the truth is far more amazing than this. The numbers are just incredible.
A few examples:
1. If the explosion of the Big Bang differed in strength by 1*10^-60 there wouldn't be a universe. There was a one in 10^60 chance that the universe exists at all. That's like firing a bullet at a one-inch bullseye on the other side of the universe 20billion light years away and hitting it 
2. If the strong nuclear force that binds atom nuclei together was +/- 5% then atoms wouldn't exist 
3. If the ratio of the mass of electrons to protons, was off by 1*10^-37 then there would be no chemistry and no DNA and therefore no life forms 
4. The big one, the cosmological constant a 1 in 1*10^120 chance of their being a universe with matter. Anything else and the universe would just be nothing but dark energy, it would collapse with no life at all 
There are many more similar arguments to be made regarding hydrogen bonding, protein folding etc. Any of these facts on their own, would make 1*10^23 chances (planets) of their being life irrelevant, the numbers are just too big. But all of these constants must be exactly precise and all at the same time. This is just impossible to have happened by chance. All these figures must be absolutely precise for life to exist. It is very improbable that life would ever have existed, you would never bet on life existing.
And yet we are here. Our universe and our planet has the exact right specifications for life to exist. Anything else would result in no life at all. The physicist Freeman Dyson after surveying all the evidence said, "it almost seems as if the universe must in some sense have known we were coming." 
From all of the scientific evidence we can see it appears that our universe and our planet were designed specifically for us to exist. They were prepared for us. This is exactly what God tells us in His word.
"In the beginning God created the heavens and the earth."
"And the Lord God planted a garden in Eden, in the east, and there he put the man whom he had formed."
Physicist Arno Penzias (who received a Nobel prize in physics for discovering Cosmic Microwave Background Radiation, evidence from the beginning of the universe) agrees and says, "The best data we have [concerning the Big Bang] are exactly what I would have predicted, had I nothing to go on but the five books of Moses, the Psalms, the bible as a whole." 
This biblical claim that we were designed and created by God in order to serve Him and worship Him has a profound affect on all of our lives. We do not exist by chance, we have purpose and a reason for being here. But this also means that God has a claim on each of our lives. We belong to Him. God created us to worship Him and enjoy Him forever, if we have ignored Him and have lived our lives without Him then this is wrong. The bible calls this sin, deliberate rebellion against God. We are all guilty of this, the bible says, "All have sinned and fall short of the glory of God." Rom 3:23. We have all chosen to live our lives for ourselves and have selfishly ignored God. God is angry at our sin and at the wrong things we have done. We deserve Gods judgement in hell. But God loves us. He has made a way we can be saved by trusting in the Lord Jesus. Paul the apostle put it this way, "The times of ignorance God overlooked, but now he commands all people everywhere to repent, because he has fixed a day on which he will judge the world in righteousness by a man whom he has appointed; and of this he has given assurance to all by raising him from the dead.” Acts 17:30-31. We can have this relationship with the God of heaven who created us, what we were made for, by coming in faith to the Lord Jesus. God has created us and therefore owns us, He commands that we come to Him in repentance-to turn away from our sins back to Him.
We cannot ignore the question of our origins. It is too important a question and has an impact on our whole lives and in fact our eternal lives after we die. Each of us must seriously consider this question and find the answer. Either we were created and designed or we just happened to exist by chance. If we were created by God, then we need to come to Him in faith to be saved. I believe that the bible is true and that we were made in Gods image. That is why I am a Christian and why I don't believe there are aliens.
 Freeman Dyson Scientific American, 224, 1971, p 50.
 Arno Penzias, New York Times on March 12, 1978.