Catholics are not forbidden from praying in private. In fact, the Church encourages her members to pray daily, both in private and in public.
Private prayer, whether spontaneous or formal, is essential to the spiritual life. Public prayer is equally important. The highest form of public prayer is called liturgical prayer, for it is the Church at prayer.
What one member or a few members do benefits all because of the doctrine of the Mystical Body of Christ, which basically states that each person is as integral a member of the Church as each organ is to a person’s body.
The symbol of Christianity is the cross, which is the intersection of a horizontal and a vertical line. The vertical line can symbolize our individual relationship with God. All Christians, including Catholics, are asked to have a personal relationship with Jesus Christ.
The horizontal bar represents the communal or ecclesial relationship of the member to the Church, be it the universal church around the world, the diocese, or the local parish. The apostles gathered together for the “breaking of the bread,” as the Mass was originally called. The disciples and other Christians gathered together in an assembly, and this was called in Greek ekklesia (in Latin ecclesia), which we translate into English as “church.”
Sunday (or Saturday evening) worship of God must be ecclesial since it has been the norm for Christians from day one. Private worship of God is allowed and encouraged on any and all days of the week. It is not a question of choosing one or the other.
Catholic Christians are expected to go to Catholic Mass each and every Sunday (or weekend) and holy day of obligation to join in communal worship of God. Private prayer is in addition to this requirement, but can take place at the person’s own discretion and choice.