God made us free, but he didn't leave us alone. Catholics do not believe in a fatalistic concept of destiny, because we believe that God created us as free and intelligent beings who are responsible for our actions. God does not leave us on our own, however, and the Church teaches that God, by his Providence, "guides all his creatures with wisdom and love to their ultimate end."
God created man with free will, and thus he is responsible for his actions. Therefore, Christians should not believe in destiny as an inevitable fate, which is a concept that comes from pagan mythology.
In ancient Greek mythology, the Fates (or Moirae) were the personification of Destiny. They were the reserved portion, the constitutive limit on each god in this mythology. This means that the Fates assigned the gods their fields of action, honors, and privileges. Since the gods could not go beyond their assigned limits, the Fates could thus act upon human beings. In this sense, their decrees were inflexible.
This representation of destiny, found also in the Latin "fatum," predates Christianity. It expresses the idea that behind the events of life, there may be something inevitable and fatal that goes beyond human freedom. It is as if certain events and facts were written in advance, such that no one can ever change anything.
Catholic thought denies that the world and events are the product of a dark force, sometimes beneficial, sometimes malevolent, that is imposed on human beings. For Christians, God created the world according to his wisdom and goodness and wanted to make his creatures share in his being, wisdom, and love.
God created man intelligent and free, and therefore responsible for his actions. Therefore, man cannot attribute the consequences of his own actions to fate.
God did not just create the world. He did not just give his creatures life and existence, but also granted them the power to participate in his work. In other words, he enabled them to cooperate in making the world more perfect and harmonious. He gave his creatures, who are endowed with intelligence and will, the dignity of acting on their own, freely.
Christian thought sets such a high value on human freedom that it goes so far as to affirm that this freedom is an "outstanding manifestation of the divine image" (CCC, No. 1705). Therefore, if man is free to act according to his intelligence, how could he be locked into predetermined decrees governing his life? Thus, man is always responsible for his voluntary behaviors; that is, he must answer for his free acts, both to the human community and to God.
Instead of believing in fate, Christians believe in divine providence. Man is created in a state of journeying toward an ultimate perfection yet to be achieved, with God. Divine Providence refers to the provisions by which God guides his creation toward this ultimate perfection.
The final perfection to which human beings are called in eternal life consists in sharing in the fullness of love, which is God (CCC, No. 221). This mystery of communion with God surpasses all understanding and description. Scripture speaks of it in images: paradise, the heavenly Jerusalem, the Father's house, happiness, light, life, peace (CCC, No. 1027).
But here in our earthly life, human beings were created in a state of journeying toward this ultimate perfection. In this journey, God does not abandon his creation to itself. He maintains us, providing his help as we live our lives.
This relation expresses man's dependence on his Creator. Recognize this dependence does not imply challenging human freedom or referring to destiny as if it were a predetermined fate. Rather, it is an act of humility, which is a source of wisdom, freedom, joy, and confidence (CCC, No. 301).
Source: Catechism of the Catholic Church, Nos. 279-324.