Once when Our Lord was coming into Capharnaum, He was approach by an official there asking Him to come and heal his son. Jesus tells him, “unless you see signs and wonders, you will not believe” (John 4:49). One might be tempted to read this as a rebuke, but it is clear from the fact that Jesus did heal his son that He was instructing His followers that miracles are an essential element for the spreading of the Faith. Miracles are one of the Motives of Credibility (CCC 156) by which the act of faith is deemed reasonable and thus we should expect to find them everywhere the gospel is preached. Our age is unique in that we no longer wonder at signs, but instead assume there is some, perhaps hitherto unknown, natural explanation for everything we experience. Immersed in such a culture, Catholics give little thought to the miraculous and the role that they might play in the conversion of many in our world.
What Are Miracles?
Miracles are, according to St. John Henry Newman, “irregularities in the economy of nature, but with a moral end…Thus while they are exceptions to the laws of one system, they may coincide with those of another.” What he means by this is not that they are mere exceptions to the physical order, but that they belong properly to Divine Providence and that God uses them with some regularity for a “moral end.” This “moral end” highlights the fact that they are signs that God uses for the very specific purpose of drawing people to the central saving mission of Christ. It is meant to be a divine stamp of approval that the message of the gospel is true. Furthermore, although we use the term colloquially for anything that causes us to wonder (like the “miracle of life”), St Thomas says that a true miracle is one that has a cause that is hidden from everyone and can only be attributed to God Himself.
In his Oath Against Modernism, Pope St. Pius X taught that it was necessary to “accept and acknowledge the external proofs of revelation, that is, divine acts and especially miracles and prophecies as the surest signs of the divine origin of the Christian religion and I hold that these same proofs are well adapted to the understanding of all eras and all men, even of this time.” Modernism has infected the Church so that many people think miracles were simply the effect of a primitive culture in which people were superstitious and did not understand the laws of nature. Belief in miracles, far from depending on ignorance of the laws of nature, requires knowledge. You cannot deem something extraordinary if you do not know what is ordinary. They were well aware that water does not directly become wine and that dead people don’t merely walk out of their tombs when commanded.

It is this Modernist infection that has caused many “theologians” and preachers to explain away the miracles of Jesus with some natural explanation. The problem with this is that if Jesus did not perform miracles then His followers can’t do likewise in His name. The power embedded in the gospel message is gone.
Miracles and Free Will
Often Christians will reject the idea that God uses miracles because it appears to impede a person’s free will. This is obviously not true when we look at examples of the gospels. For example, many people saw the three hours of darkness that preceded the Crucifixion, but presumably only the Centurion believed. That is because the act of belief is not in the miracle per se, but the consequences of the miracle. The Centurion cooperated with the grace to believe that “this truly is the Son of God” while the others simply accepted the fact that they had experienced something unexplainable. A similar thing happens when Jesus raises Lazarus from the dead. The Jews were unwilling to accept the consequence of the miracle (Jesus was Who He said He was) and instead wanted to kill Him and Lazarus both. The point is that each miracle has a grace of belief attached to it that not everyone will cooperate with.
Somewhat tangentially, the example of the three hours of darkness serves as a good example of rejecting the miraculous. Most people would say that it was merely an eclipse. The problem of course with that is that an eclipse normally lasts for about 8 minutes and not three hours. Furthermore, the Jewish Passover always occurs with a full moon (Lev. 23:5), and it is astronomically impossible to have an eclipse at such a time. Christ must have hung on the Cross in almost complete darkness and everyone around must have known that something was going on.
After Our Lord cursed the fig tree, He told the Apostles “Have faith in God. Truly, I say to you, whoever says to this mountain, ‘Be taken up and cast into the sea,’ and does not doubt in his heart, but believes that what he says will come to pass, it will be done for him. Therefore I tell you, whatever you ask in prayer, believe that you receive it, and you will ” (Mk 11:22-24). He expects His followers not only to believe in His miracles but to believe that they will do “greater works than these” (John 14:12). He cautions them that the only true obstacle is doubt and so it is important that we come to expect the miraculous to occur.