The Church generally is wary of claims of prophecy. Even if he is legitimate, what he claims to have received falls under private revelation.
Archdiocese of Denver statement:
After reviewing the commission’s findings and in keeping with his pastoral office, Archbishop Samuel J. Aquila of Denver has decided to strongly advise the faithful to exercise prudence and caution in regards to Mr. Charlie Johnston’s alleged divine visions and messages. As has been demonstrated with other alleged apparitions, the danger exists of people placing greater faith in a prediction than in Christ’s words and promises.
For these reasons, Mr. Johnston will also not be approved as a speaker in the Archdiocese of Denver.
Catechism of the Catholic Church:
**67 **Throughout the ages, there have been so-called “private” revelations, some of which have been recognized by the authority of the Church. They do not belong, however, to the deposit of faith. It is not their role to improve or complete Christ’s definitive Revelation, but to help live more fully by it in a certain period of history. Guided by the Magisterium of the Church, the sensus fidelium knows how to discern and welcome in these revelations whatever constitutes an authentic call of Christ or his saints to the Church.
If anyone says to you then, ‘Look, here is the Messiah!’ or, ‘There he is!’ do not believe it. False messiahs and false prophets will arise, and they will perform signs and wonders so great as to deceive, if that were possible, even the elect. Behold, I have told it to you beforehand. So if they say to you, ‘He is in the desert,’ do not go out there; if they say, ‘He is in the inner rooms,’ do not believe it.
Jesus began to say to them, “See that no one deceives you. Many will come in my name saying, ‘I am he,’ and they will deceive many. When you hear of wars and reports of wars do not be alarmed; such things must happen, but it will not yet be the end. Nation will rise against nation and kingdom against kingdom. There will be earthquakes from place to place and there will be famines. These are the beginnings of the labor pains…
…If anyone says to you then, ‘Look, here is the Messiah! Look, there he is!’ do not believe it. False messiahs and false prophets will arise and will perform signs and wonders in order to mislead, if that were possible, the elect.