Ambrosiaster : Paul says this to encourage the person concerned to suppress his shyness and receive the ability to profess and lay claim to faith. — COMMENTARY ON PAUL'S EPISTLES Augustine of Hippo : Without the spirit of faith no one will rightly believe. Without the spirit of prayer no one will profitably pray. It is not that there are so many spirits, "but in all things one and the same Spirit works, who apportions to each one individually as he wills." — LETTER 191, To Sixtus Cyril of Jerusalem : This faith which is given by the Spirit as a grace is not just doctrinal faith but a faith which empowers activities surpassing human nature, a faith which moves mountains.… For just as a grain of mustard seed is of little bulk but of explosive energy, taking a trifling space for its planting and then sending out great branches all around, so that when it is grown it can give shelter to the birds, so in like manner the faith present in one's soul achieves the greatest things by the most summary decision. For such a one places the thought of God before his mind and as enlightenment of faith permits it, beholds God. His mind also ranges through the world from end to end, and with the end of this age not yet come, beholds the judgment already, and the bestowal of the promised rewards. — Catechetical Lecture 5.11 Theodoret of Cyrus : The faith mentioned here is not the kind given to every believer but the kind which can move mountains. — COMMENTARY ON THE FIRST EPISTLE TO THE CORINTHIANS 244