Catechism of the Catholic Church

Now, however, "we walk by faith, not by sight"; we perceive God as "in a mirror, dimly" and only "in part." Even though enlightened by him in whom it believes, faith is often lived in darkness and can be put to the test. The world we live in often seems very far from the one promised us by faith. Our experiences of evil and suffering, injustice, and death, seem to contradict the Good News; they can shake our faith and become a temptation against it. (2846, 309, 1502, 1006)