I do not believe that we are the only ones in the universe, but that does not mean the aliens exist. The universe is very vast it does not actually mean that the earth are the only beings. It means that God has decided that humans of Earth are not ready to make contact outside of their planet until salvation is rewarded to all.
Since the entire earth is going through a testing period we will have to wait until the time of release can be granted to us, Revelation 3:10. Because certain ones are Christians and others are not, we have no contact with God at the moment but that does not mean God does not exist, Matthew 24:29-30. The time will come soon when all will be revealed, and we will understand what is going on, Issiah 2:2-4.