The Catechism in Questions & Answers

78. Why should human beings concern themselves with the invisible?

Man is an entity consisting of spirit, soul, and body (cf. 1 Thessalonians 5: 23). The body is mortal and thus belongs to the visible creation of God. Soul and spirit thus belong to the invisible creation of God. Because soul and spirit continue to exist even after physical death, it is important to concern oneself with the invisible.
The attitude which a person adopts toward God during earthly life will have consequences for his existence in the beyond. This insight can help him resist the temptations of the Devil and lead a life that is pleasing to God.
The significance of the invisible is clarified by Apostle Paul: “For our light affliction, which is but for a moment, is working for us a far more exceeding and eternal weight of glory” (2 Corinthians 4: 17-18). Occupying themselves with the invisible therefore helps human beings process that which they experience.