Acts 20:28-38 / John 17:11-19
In the theory of evolution, a species can evolve and can develop some additional features or characteristics.
But no matter how a species may evolve, it cannot turn into another species of another genetic variation.
So for example, a dog can't turn into a cat, nor can it turn into a pig. Even when there is evolution in the species, the dog's genetic heredity will remain more or less the same.
Needless to say then, a sheep can't turn into a wolf, nor can a wolf turn into a sheep. Naturally speaking, that is impossible.
But spiritually speaking, a person can change from good to bad, or from bad to good.
In the 1st reading, St. Paul used the image of fierce wolves attacking and having no mercy on the flock to refer to the enemies of the Church.
And he says that even from within the Church, there will be people who will come up with a travesty of the truth and cause division.
It can be said of those people that the sheep have become like wolves.
Yet it is also the mission of the Church to turn those wolves into sheep.
That can only happen when the sheep listen to the voice of the Good Shepherd and go the way He is leading them.
When the sheep follow the Shepherd, even the wolves will be converted.