A fourth-century church father and catechist, Cyril of Jerusalem, had an interesting way of preparing new members of the church. He began with the sacraments. The connection is actually quite logical. He is preparing the members for baptism and his job is to explain the world that baptism will bring them into.
His first lecture is not explicitly about baptism. The lecture is full of the baptismal imagery of washing and purity. He lays out his theology of baptism in lecture three. This is part of a lecture series which is filled with the most important doctrines of the Christian faith: the Trinity and the Work of Christ.
Cyril seems to have a subconscious understanding that baptism externalises the Christian faith. As a ritual, it says something about who the baptizants are and who they will be. Baptism is full of the content of the Christian faith. In this way, Baptism provides a framework for all Christian doctrine. We might add, with the reformers, that this is because Baptism points to the work of Jesus Christ, which is the centre of all Christian doctrine.