Here is a clip from the letter as posted by Catholic News Agency:
There is a phrase Jesus uses in the Gospel, which, by the way, Cardinal Urosa just mentioned on television, which says: “Not everyone who says Lord, Lord, will enter the Kingdom of Heaven, but only he who does the will of my Heavenly Father.” You have displayed various acts of faith and trust in God, calling him “My sweet God,” hugging and kissing crucifixes, visiting the Shrine of Santo Cristo de la Grita and many other similar things.
If this is all sincere, it is very praiseworthy and I applaud you for it. However, unfortunately this is not enough to receive God’s forgiveness and enter into the kingdom of Heaven. Repairing the evil and the injustices that have been done to people and to institutions is also strictly necessary, and in your pride you have committed such acts on innumerable occasions. Read more on this here.