The topic of the stigmata is very serious and unsettling. The Church takes a very critical and — with good reason — very rigorous look at specific cases before talking about this topic. This is why it has made a positive pronouncement only in a few cases and after rigorous medical and theological studies.
The stigmata represent a sign of Christ’s sufferings during the Passion, and therefore they constitute a theological statement; that is to say, they are a faithful reproduction in certain people of Jesus’ wounds at the moment of his crucifixion, above all in what refers to the place of the wounds (feet, hands, side and head).
In the cases the Church has approved, the stigmata are a grace of God granted to few saints; the stigmata are physical manifestations of Christian mysticism.
We must keep in mind that when the Church recognizes a phenomenon as authentic, it accepts the phenomenon but in no case does it propose that it be believed as a doctrine of faith.
The Church doesn’t canonize anyone just because they have the stigmata. What the Church does when it canonizes is recognize the exemplary Christian life of a saint, whether or not he or she has the stigmata.
The phenomenon of the stigmata is a sign of the reality of Christ’s passion on the Cross. By God’s will, certain saints who have loved and meditated on the sacrifice of Christ crucified have participated in his sufferings. They offer those sufferings with the same spirituality as Saint Paul, who said, "I am now rejoicing in my sufferings for your sake, and in my flesh I am completing what is lacking in Christ’s afflictions for the sake of his body, that is, the church." (Colossians 1:24)
Actually, some people affirm that the apostle Paul himself had the stigmata, and that when he says, "… I carry the marks of Jesus branded on my body" (Galatians 6:17), he wasn’t saying it metaphorically, but literally.
For stigmatists, the wounds of Christ on their bodies are an unmerited grace; therefore, if they are a form of grace, God is the one who gives them. Stigmatists do not ask for these mystical experiences.
But, why does God grant the stigmata? Through the stigmata, God expresses his pleasure in the holiness of life related to the conscious acceptance of the Cross taken up spiritually. It is, then, an experience of suffering colored with joy for the grace received.
A stigmatist receives the mission of being a prophet to remind mankind of the realities that are truly important. They help us to see the extremes to which Christ went to redeem us. They help those who suffer to conform themselves to Christ, offering their own sufferings for the salvation of souls.
What are the criteria that the Church uses to determine whether or not the stigmata are authentic?
1. The stigmata are located in the same places as the five wounds of Christ.
2. The stigmata all appear at the same time.
3. The stigmata appear spontaneously while the person prays in ecstasy.
4. They cannot be explained by natural causes.
5. They do not deteriorate into necrosis.
6. The do not give off a bad smell; on the contrary, sometimes it is said they smell of flowers.
7. They do not become infected.
8. They bleed daily and profusely.
9. They remain unchanged despite treatment. They do not become worse.
10. They cause a significant modification of the bodily tissues.
11. They do not close perfectly and instantaneously.
12. They are accompanied by intense physical and moral suffering, as from participating in the sufferings of Christ. (The lack of pain is a bad sign and a cause for doubt.)
As if the above were not enough, the entire life of the person involved is also studied. He or she must be a person who practices Christian virtues heroically — in particular, their great love for humility and for the cross should stand out.