If a miracle is a sign it will happen in a context that heavily stresses creation from nothing by God but no miracle does that!

Miracles are stated by religion to be creation acts of God – bringing out of nothing. If God does miracles then he will only do them among people who believe in the creation of the universe where there was not anything.  Why?  For as Christianity says, it is the basis of all its teaching.  It expresses the complete dependence of all on God.  Doctrines such as Jesus being both God and man and Jesus' body being fed to us in the form of bread make no sense without it.  The Church uses the doctrine to defend and explain and justify Jesus' command that we must offer and give our whole being to God in love.

Be warned that creation from nothing means more than just things appearing at the beginning of time.  It means it is ongoing creation.  If God withdrew his consent all things would vanish and there would not be anything.

It is known that this doctrine of ex nihilo comes from pagan philosophical speculation and not the Bible.

The Jews didn’t believe in it as an official doctrine.  Yet the Old Testament says that miracles happened among the Jews and reports bigger ones than any reported in the time of Jesus Christ.  Worse, Jesus did not mention creation ex nihilo at all. 

If he had, he would have been regarded as insane for the prevailing view of thinkers at the time was that "out of nothing nothing comes".

Now nobody can prove that God really created in any miracle. He might just use the existing forces of nature to do the wonders. For example, he might use our proneness to illusion and error to make us think that a miracle happened or that somebody healthy had cancer that was thought to have disappeared inexplicably. To put down a miracle as a creation act of God is to guess. If we have to guess then miracles are no good. If we have to guess that miracles are the work of God then why not simply guess that there is a God? You are still guessing anyway. It would be better to simply guess that there is a God than to guess that there is a God and he does miracles for better one guess than two. Remember, it is decency and rationality to keep things simple. To cite miracles as evidence for God or creator or a religion is the same as citing the sawing of a woman in half and putting her together again as proof of a magician’s healing powers.
 
A miracle is no good for you cannot prove a creative act was involved any more than you can prove a creative act was involved when something mundane happens. The creation would be the most important thing. And the most important message. A miracle of creation contradicts our uniform experience. Even if the universe was created by God we cannot experience that. Nor can we sense that individual acts of creation happen now on a small scale. We can believe in things and we do believe in things that are not religious or magical against our uniform experience. So it seems the argument that a miracle cannot be believed in is wrong. Or is it? Believing that a statue of Mary bled is not the same as believing it was a creation miracle. You cannot prove that the blood was not supernaturally transported from somewhere as opposed to being supernaturally created. No in fact the argument has nothing to do with this at all. What is the problem? The problem is that you don’t see or detect the creation. A miracle is never believed in. It is only assumed.

A quote

"We also have the tendency to consider a miracle as being something from nothing, but it is not. If we consider a miracle, such as the splitting of the Red Sea, when the Jews left Egypt, we will see that although it is a miraculous deed, still it is not something from nothing. What happens in a miracle is that the nature of the matter, in our case, water, changes temporarily. The nature of water is that it can not stand, that is to say, one drop on top of the next, like a stone. The miracle involves the changing of the nature of water, suspending the laws of liquids and substituting the laws of solids in its place. When the Jews left Egypt and the water split and stood like a wall, the laws of nature were suspended and changed."

Critique - the account does not say if something did or did not come from nothing.  God surely can create rainclouds on a day when they should not happen and we would not notice that they came from nothing.  God changing nature would be worse than God just sticking something into the middle of nature out of nothing.  A brick that floats in mid-air means it is no longer the case that bricks don't do that.

If the sun rises that is something from nothing.  The quote forgets that creation from nothing is happening now according to Christian doctrine.
 
finally

Christians can't see if a miracle comes from nothing. They only guess it. If they have to guess then they can't say for sure that God is doing the miracle. So the miracle then is not a sign from Heaven at all. It is just a curiosity. When they talk about their faith in a God of miracles and tell you about the miracles they should admit that they are only guessing. Instead of harassing or manipulating people to believe, they should let them guess that the miracles are nonsense if they want to! The miracles tales are not really respectful to God either. There is no concern about saying God did creative acts that he did not do at all.

Further Reading ~
 
A Christian Faith for Today, W Montgomery Watt, Routledge, London, 2002
Answers to Tough Questions, Josh McDowell and Don Stewart, Scripture Press, Bucks, 1980
Apparitions, Healings and Weeping Madonnas, Lisa J Schwebel, Paulist Press, New York, 2004
A Summary of Christian Doctrine, Louis Berkhof, The Banner of Truth Trust, London, 1971
Catechism of the Catholic Church, Veritas, Dublin, 1995
Catholicism and Fundamentalism, Karl Keating, Ignatius Press, San Francisco, 1988
Enchiridion Symbolorum Et Definitionum, Heinrich Joseph Denzinger, Edited by A Schonmetzer, Barcelona, 1963
Looking for a Miracle, Joe Nickell, Prometheus Books, New York, 1993
Miracles, Rev Ronald A Knox, Catholic Truth Society, London, 1937
Miracles in Dispute, Ernst and Marie-Luise Keller, SCM Press Ltd, London, 1969
Lourdes, Antonio Bernardo, A. Doucet Publications, Lourdes, 1987
Medjugorje, David Baldwin, Catholic Truth Society, London, 2002
Miraculous Divine Healing, Connie W Adams, Guardian of Truth Publications, KY, undated
New Catholic Encyclopaedia, The Catholic University of America and the McGraw-Hill Book Company, Inc, Washington, District of Columbia, 1967
Raised From the Dead, Father Albert J Hebert SM, TAN, Illinois 1986
Science and the Paranormal, Edited by George O Abell and Barry Singer, Junction Books, London, 1981
The Demon-Haunted World, Carl Sagan, Headline, London, 1997
The Book of Miracles, Stuart Gordon, Headline, London, 1996
The Case for Faith, Lee Strobel, Zondervan, Grand Rapids, Michigan, 2000
The Encyclopaedia of Unbelief Volume 1, Gordon Stein, Editor, Prometheus Books, New York, 1985
The Hidden Power, Brian Inglis, Jonathan Cape, London, 1986
The Sceptical Occultist, Terry White, Century, London, 1994
The Stigmata and Modern Science, Rev Charles Carty, TAN, Illinois, 1974
Twenty Questions About Medjugorje, Kevin Orlin Johnson, Ph.D. Pangaeus Press, Dallas, 1999
Why People Believe Weird Things, Michael Shermer, Freeman, New York, 1997