First, let’s define “aliens” as “beings capable of making moral choices, having intellect, emotion, and a will.” Next, a few scientific facts:
1. Men have sent spacecraft to nearly every planet in our solar system. After observing these planets, we have ruled out all but Mars and possibly a moon of Jupiter as being able to support life.
2. In 1976, the U.S.A. sent two landers to Mars. Each had instruments that could dig into the Martian sand and analyze it for any sign of life. They found absolutely nothing. In contrast, if you analyzed soil from the most barren desert on earth or the most frozen dirt in Antarctica, you would find it teeming with micro-organisms. In 1997, the U.S.A. sent Pathfinder to the surface of Mars. This rover took more samples and conducted many more experiments. It also found absolutely no sign of life. Since that time, several more missions to Mars have been launched. The results have always been the same.
3. Astronomers are constantly finding new planets in distant solar systems. Some propose that the existence of so many planets proves that there must be life somewhere else in the universe. The fact is that none of these has ever been proved to be anything close to a life-supporting planet. The tremendous distance between Earth and these planets makes it impossible to make any judgments regarding their ability to sustain life. Knowing that Earth alone supports life in our solar system, evolutionists want very badly to find another planet in another solar system to support the notion that life must have evolved. There are many other planets out there, but we certainly do not know enough about them to verify that they could support life.
So, what does the Bible say? The earth and mankind are unique in God’s creation. Genesis 1 teaches that God created the earth before He even created the sun, the moon, or the stars. Acts 17:24, 26 states that “the God who made the world and everything in it is the Lord of heaven and earth and does not live in temples built by hands—he made every nation of men, that they should inhabit the whole earth; and he determined the times set for them and the exact places where they should live.”
Originally, mankind was without sin, and everything in the world was “very good” (Genesis 1:31). When the first man sinned (Genesis 3), the result was problems of all sorts, including sickness and death. Even though animals have no personal sin before God (they are not moral beings), they still suffer and die (Romans 8:19–22). Jesus Christ died to remove the punishment that we deserve for our sin. When He returns, He will undo the curse that has existed since Adam (Revelation 21–22). Note that Romans 8:19–22 states that all of creation eagerly waits for this time. It is important to also note that Christ came to die for mankind and that He died only once (Hebrews 7:27; 9:26–28; 10:10).
If all of creation now suffers under the curse, any life apart from the earth would also suffer. If, for the sake of argument, moral beings do exist on other planets, then they also suffer; and if not now, then someday they will surely suffer when everything passes away with a great noise and the elements melt with fervent heat (2 Peter 3:10). If they had never sinned, then God would be unjust in punishing them. But if they had sinned, and Christ could die only once (which He did on earth), then they are left in their sin, which would also be contrary to the character of God (2 Peter 3:9). This leaves us with an unsolvable paradox—unless, of course, there are no moral beings outside of the earth.
What about non-moral and non-sentient life forms on other planets? Could algae or even dogs and cats be present on an unknown planet? Presumably so, and it would not do any real harm to any biblical text. But it would certainly prove problematic when trying answer questions like “Since all of creation suffers, what purpose would God have in creating non-moral and non-sentient creatures to suffer on distant planets?”
In conclusion, the Bible gives us no reason to believe that there is life elsewhere in the universe. In fact, the Bible gives us several key reasons why there cannot be. Yes, there are many strange and unexplainable things that take place. There is no reason, though, to attribute these phenomena to aliens or UFOs. If there is a discernable cause to these supposed events, it is likely to be spiritual, and more specifically, demonic, in origin.
 Got Questions Ministries. (2010). Got Questions? Bible Questions Answered. Bellingham, WA: Logos Bible Software.