"Increase our faith" (Lk 17,5)
The word “faith” has one syllable but two meanings. First of all it is concerned with doctrine and it denotes the assent of the soul to some truth. Faith in this sense brings blessing and salvation to the soul, as the Lord said: “He who hears my word and believes him who sent me, has eternal life.” (Jn 5,24)...
The word “faith” has a second meaning: it is a particular gift and grace of Christ. “To one is given through the Spirit the utterance of wisdom, and to another the utterance of knowledge according to the same Spirit, to another faith by the same Spirit, to another gifts of healing” (1Cor 12,8-9). Faith in the sense of a particular divine grace conferred by the Spirit is not, then, primarily concerned with doctrine but with giving a person powers quite beyond their natural capability. Whoever has this faith will say to the mountain: “Move from here to there,” and it will move, and anyone who can in fact say these words through faith and “believe without hesitation that they will come to pass,” (Mk 11,23) receives this particular grace. It is to this kind of faith that the Lord's words refer: “If you have faith as a grain of mustard seed.” Now a mustard seed is small in size but its energy thrusts it upwards with the force of fire. Small are its roots, great the spread of its boughs, and once it is fully grown the birds of the air find shelter in its branches (Mt 13,32). So too, in a flash, faith can produce the most wonderful effects in the soul.
Illumined by faith, the soul gazes at the glory of God as far as human nature allows and, ranging beyond the boundaries of the universe, it has a vision, before the consummation of all things, of the judgment and of God making good the rewards he promised. As far as it depends on you then, cherish this gift of faith that leads you to God and you will then receive the higher gift which no effort of yours can reach, no power of yours attain.