To understand the Catholic beliefs about suffering a good read is
APOSTOLIC LETTER
SALVIFICI DOLORIS
OF THE SUPREME PONTIFF
JOHN PAUL II
- As we see from the examples quoted, we find in Sacred Scripture an extensive list of variously painful situations for man. This varied list certainly does not exhaust all that has been said and constantly repeated on the theme of suffering by the book of the history of man (this is rather an “unwritten book”), and even more by the book of the history of humanity, read through the history of every human individual.
It can be said that man suffers whenever he experiences any kind of evil. In the vocabulary of the Old Testament, suffering and evil are identified with each other. In fact, that vocabulary did not have a specific word to indicate “suffering”. Thus it defined as " evil" everything that was suffering(22). Only the Greek language, and together with it the New Testament (and the Greek translations of the Old Testament), use the verb * = “I am affected by … I experience a feeling, I suffer”; and, thanks to this verb, suffering is no longer directly identifiable with (objective) evil, but expresses a situation in which man experiences evil and in doing so becomes the subject of suffering. Suffering has indeed both a subjective and a passive character (from “patior”). Even when man brings suffering on himself, when he is its cause, this suffering remains something passive in its metaphysical essence.
This does not however mean that suffering in the psychological sense is not marked by a specific “activity”. This is in fact that multiple and subjectively differentiated “activity” of pain, sadness, disappointment, discouragement or even despair, according to the intensity of the suffering subject and his or her specific sensitivity. In the midst of what constitutes the psychological form of suffering there is always an experience of evil, which causes the individual to suffer.
Thus the reality of suffering prompts the question about the essence of evil: what is evil?
This questions seems, in a certain sense, inseparable from the theme of suffering. The Christian response to it is different, for example, from the one given by certain cultural and religious traditions which hold that existence is an evil from which one needs to be liberated. Christianity proclaims the essential good of existence and the good of that which exists, acknowledges the goodness of the Creator and proclaims the good of creatures. Man suffers on account of evil, which is a certain lack, limitation or distortion of good. We could say that man suffers because of a good in which he does not share, from which in a certain sense he is cut off, or of which he has deprived himself. He particularly suffers when he a ought"—in the normal order of things—to have a share in this good and does not have it.
Thus, in the Christian view, the reality of suffering is explained through evil, which always, in some way, refers to a good.
w2.vatican.va/content/john-paul-ii/en/apost_letters/1984/documents/hf_jp-ii_apl_11021984_salvifici-doloris.html
I would like to point out that we are reminded that suffering and evil are identified with each other. Something cannot be both an evil and a blessing from God at the same time. They are completely opposed to each other.