§162

Faith is an entirely free gift that God makes to man. We can lose this priceless gift, as St. Paul indicated to St. Timothy: "Wage the good warfare, holding faith and a good conscience. By rejecting conscience, certain persons have made shipwreck of their faith." To live, grow and persevere in the faith until the end we must nourish it with the word of God; we must beg the Lord to increase our faith; it must be "working through charity," abounding in hope, and rooted in the faith of the Church.

Faith makes us taste in advance the light of the beatific vision, the goal of our journey here below. Then we shall see God "face to face", "as he is". So faith is already the beginning of eternal life:
When we contemplate the blessings of faith even now, as if gazing at a reflection in a mirror, it is as if we already possessed the wonderful things which our faith assures us we shall one day enjoy.