Many western Churches, Catholic and Protestant, catechetical materials (and worship materials, for that matter) are produced commercially without any specific connection to the structure of the Church itself. In other Churches, including our own, many curriculum materials are produced by the Church Itself and so are an actual statement of the faith of the entire community. Some materials, such as the God With Us series, are produced by a number of Byzantine Churches together; others are published by our own diocese. All these resources are approved by all the bishops of the respective Churches. We believe that catechesis, like liturgy, is a function of the Church, not of each individual catechist or group of catechists. This is why many curriculum materials are mandated (obligatory) in our Church in the same way that the typicon of our Church prescribes the liturgical services for the parish.