“Do you see this woman? I entered your house, you gave me no water for my feet, but she has wet my feet with her tears and wiped them with her hair. You gave me no kiss, but from the time I came in she has not ceased to kiss my feet. You did not anoint my head with oil, but she has anointed my feet with ointment. Therefore I tell you, her sins, which are many, are forgiven, for she loved much; but he who is forgiven little, loves little.” And he said to her, “Your sins are forgiven.” Then those who were at table with him began to say among themselves, “Who is this, who even forgives sins?” And he said to the woman, “Your faith has saved you; go in peace.” [Luke 7:44-50, emphasis added]
Were this woman’s sins forgiven because of her faith or because of her love? Jesus attributes her salvation to both. Now, I have heard some Protestants twist themselves into knots trying to deny that faith is a human act just because they hold to an extreme monergism. But is love a human act or not? Of course it is: it is an act that God gave her grace to do, and she could not have loved or believed God without His grace. We are saved by grace, but never against our own wills.
Aquinas, Etc. 
Faith is a “first step” act. All we need to do is take the first step and dare to believe without any evidence or proof at all. God will do the rest. It doesn’t require much Faith to take the first step. Only half a mustard seed’s worth.
Faith is to believe when your common sense tells you not to.
God bless.