Recommended Book: First Epistle of Clement to the Corinthians - Kindle Edition (get Kindle app for phone) (paid link)
O my God, I firmly believe that you are one God in three divine Persons, Father, Son, and Holy Spirit; I believe that your divine Son became man and died for our sins, and that he will come to judge the living and the dead. I believe these and all the truths which the Holy Catholic Church teaches, because you revealed them, who can neither deceive nor be deceived.