The image of the Madonna in glass windows is a miracle to many devout people and does not need explanation. But to other equally devout people it can be scientifically explained away. Obviously, this does not mean that miracles should only be accepted because they have some scientific or other evidence to back them up, particularly if it helps establish the reality of the miracle itself. Doing so doesn't detract in any way from God's wondrous orderings of the heavens. Demonstrating that miracles took place may be helpful to some people, but it won't convince all.
Many people use arguments about miracles as a smokescreeen.
I have met several people who don't want to believe and don't want to be challenged to believe and would put up any excuse to prevent themselves from examining the claims of Jesus Christ to be God's Messiah. Demostrate the reality of a miracle and then they will find some other excuse. Conviction about religious belief and its associated historical basis is not by rational means alone, but they can help.