"The one word faith can have two meanings. One kind of  faith concerns doctrines. It involves the soul's ascent to an acceptance of some particular matter...The other kind of faith is given by Christ by means of a special grace...May you have the faith which depends on you and is directed to God, that you may receive from him that faith too which transcends man' capacity." (St. Cyril of Jerusalem)

Both forms of faith are the result of God's grace. To make an act of faith in the mystery of the Trinity can only happen through the grace of God. This act of faith draws me closer to God. The other act of faith enables me to be an instrument of God's mighty deeds in the life of others. It is the grace to follow and act on the lead of the Holy Spirit in regards to others. For instance, we are talking to someone and the Lord puts on our heart that we should say something to this person. We step out in faith and expressed what the Lord put on our hearts and it ministers to the other. This is not an act of faith in a doctrine but  in the move of the Spirit in my life for the sake of another. Be attentive to the grace of the Holy Spirit in both and do not be afraid to act on the second form of faith as a witness.