Living the profession of faith
Amen expresses trust and assent. At the close of the Creed it gathers a profession of faith into a personal response to the faithful God. The word also belongs to prayer and the liturgy, where saying it calls for attention rather than habit alone. Belief becomes credible as it shapes worship, decisions, and relationships.
Follow the sources
An original library introduction, with sources for further study. This is a starting point rather than a complete treatment or a finished formation lesson.