Extraterrestrial Life

The Church does not have a specific teaching on extra-terrestrial life. The subject, however, is tied up with the whole question of biological evolution, about which the Church has shown great reserve (cf. Pope Pius XII, Humani generis). Can life come about by chance processes at work in the natural physical and chemical operation of the universe? If this can occur on earth, then presumably it can occur elsewhere, given the right conditions. This much can be said affirmatively, all rational embodied creatures (those with a body and a soul), wherever they are in the universe, have Christ as their Head and Redeemer (Col. 1:15-20). If intelligent life exists elsewhere, then it has a relationship with the Incarnation and Redemption.

However, despite all the glib claims by agnostic scientists that intelligent life must exist somewhere else among the billions and billions of galaxies, the best models and mathematical analyses show the probably of an earth-like environment anywhere in the universe to be practically zero. The fact that there is life on Earth, therefore, is an anomaly that came about by design, not chance. Cosmologists call it the Anthropic (man) Principle, in order to get away from filling the holes in the scientific models with God. As persons and believers they may do so, in their role as scientists they may not.

So, if intelligent life exists somewhere else, it will be by design, as well. And, that life will be incorporated into God's plan, as St. Paul certainly declares of everything that IS. 

Pope St. John Paul II stated that we should not argue from science to what we believe. Physics does not exist to prove Genesis, for example. However, the witness of science to the realities to which faith also testifies is increasingly evident. Over time the way in which science and faith can be reconciled becomes clearer. Since all truth has God as its author, it is exactly what we would expect to occur.