The Need & Power of Witness
The first form of witness is the very life of the missionary, of the Christian family, and of the ecclesial community, which reveal a new way of living. The missionary who, despite all his or her human limitations and defects, lives a simple life, taking Christ as the model, is a sign of God and of transcendent realities. But everyone in the Church, striving to imitate the Divine Master, can and must bear this kind of witness; in many cases it is the only possible way of being a missionary.
The evangelical witness which the world finds most appealing is that of concern for people, and of charity toward the poor, the weak and those who suffer. The complete generosity underlying this attitude and these actions stands in marked contrast to human selfishness. It raises precise questions which lead to God and to the Gospel. A commitment to peace, justice, human rights and human promotion is also a witness to the Gospel when it is a sign of concern for persons and is directed toward integral human development.
from Mission of the Redeemer (Remdemptoris Missio) by Pope John Paul II #42