Final answer:
Francis of Assisi indirectly called for reform through his lifestyle; Martin Luther directly challenged Church practices, leading to the Protestant Reformation; Teresa of Avila emphasized personal spirituality within the Church. The characteristics of a reformer include integrity, faith understanding, commitment to change, and the ability to inspire.
Step-by-step explanation:
Francis of Assisi, Martin Luther, and Teresa of Avila approached the need for reform in the Catholic Church in distinct ways. Francis of Assisi focused on living a life of poverty and emulating Jesus Christ, thus setting an example that indirectly called for a return to the basic values of Christianity. In contrast, Martin Luther's approach was more direct, as he challenged the Church's practices and doctrines, advocating for justification by faith alone and the authority of Scripture over tradition, leading to the Protestant Reformation. Teresa of Avila worked within the Church to deepen the spiritual life, founding the Discalced Carmelites and emphasizing a personal relationship with Christ.
Regarding the need for reform in today's church, opinions vary and depend on perspectives and identified issues. Characteristics a reformer should have include integrity, deep understanding of the faith, a commitment to positive change, and the ability to inspire and engage others in a constructive dialogue.