Final answer:
The Brethren, being part of the Anabaptist movement, emphasized adult baptism and thus stood upon a gospel that highlighted conscious faith and personal commitment over traditional infant baptism.
Step-by-step explanation:
The gospel that the Brethren received and stood upon led them to be defined by a belief in adult baptism over infant baptism, with a strong commitment to their religious principles. The Anabaptists, such as the Swiss Brethren, believed that adult baptism was necessary for an individual to meaningfully renounce sin and make a declaration of faith. This was in contrast to the dominant Catholic and Protestant belief in the efficacy of infant baptism to remove original sin. By adhering to this distinct understanding of baptism, the Brethren established themselves as a group that prioritized individual confession of faith and conscious commitment to Christianity. This foundational belief shaped their community and religious identity during the tumultuous period of the sixteenth century, which saw many religious reforms and the formation of new denominations.