Faith is not some state of feeling we get ourselves into. It is much simpler than that. It is simply believing in God and therefore believing everything he has revealed -- no matter how we feel. "God said it, so I believe it, and that settles it."
Feelings are influenced by external things, like fashions and fads, wind and weather, diet and digestion. But when God gives us the gift of faith, he gives it from within, from within our own free will.
The devil can influence our feelings, but he has no control over our faith.
We are not responsible for our (unfree) feelings, but we are responsible for our (free) faith.
Yet, though faith is not a feeling, it often produces feelings: of trust, peace, gratitude, and confidence, for instance. And faith can also be aided by feelings: for instance, when we feel trustful or grateful to someone, God or man, it is much easier for us to believe him than we feel mistrustful or ungrateful.
But even when we do not feel trustful or peaceful, we can still believe. Faith is not dependent on feelings. It is dependent on facts: divinely revealed facts.
There is a Chinese parable about faith and feeling. Fact, Faith, and Feeling are three men walking along the top of a well. As long as Faith keeps his eyes on Fact, ahead of him, all three keep walking. But when Faith takes his eyes off Fact and turns around to worry about how Feeling is doing, both Faith and Feeling fall off the wall. (But Fact never does.)
Catholic Christianity: A Complete Catechism of Catholic Beliefs based on the Catechism of the Catholic Church by Peter Kreeft