If I lived in Italy and someone asked me, 'How do I get to Rome?' I would first ask, 'well, where are you starting from?' Similarly, in order to effectively evangelize, we have to know where the person we are talking with 'is coming from' and how various words and concepts differ between our diverse faiths. So, to explain our faith we really need to have some understanding of their faith, i.e., we need to consider ecumenical matters.
On March 25th, 1993, His Holiness Pope John Paul II addressed this need and approved this DIRECTORY FOR THE APPLICATION OF PRINCIPLES AND NORMS ON ECUMENISM.
Here are a few quotes from this long and comprehensive document, to encourage you to follow the link above and read the entire document:
"Be careful to respect the lively faith of other Churches and ecclesial Communities which preach the Gospel, and rejoice in the grace of God that is at work among them."First, at the family level:
"In the interest of greater understanding and unity, both parties should learn more about their partner's religious convictions and the teaching and religious practices of the Church or ecclesial Community to which he or she belongs. To help them live the Christian inheritance they have in common, they should be reminded that prayer together is essential."
"The family, called the "domestic church" by the Second Vatican Council, is the primary place in which unity will be fashioned or weakened each day through the encounter of persons, who, though different in many ways, accept each other in a communion of love. It is also there that care must be taken not to entertain prejudices, but on the contrary to search for the truth in all things."And, at a broader level:
"When speaking of other Churches and ecclesial Communities, it is important to present their teaching correctly and honestly. Among those elements by which the Church itself is built up and given life, some—even many and very valuable ones—are to be found outside the visible limits of the Catholic Church. The Spirit of Christ therefore does not refuse to use these communities as means of salvation. Doing this also puts in relief the truths of faith held in common by various Christian confessions. This will help Catholics both to deepen their own faith and to know and esteem other Christians, thus making easier the search in common for the path of full unity in the whole truth."And, reaching even beyond the Christian faith:
"There are increasing contacts in today's world between Christians and persons of other religions. These contacts differ radically from the contacts between the Churches and ecclesial Communities, which have for their object the restoration of the unity Christ willed among all his disciples and are properly called ecumenical. But in practice they are deeply influenced by, and in turn influence ecumenical relationships. Through them Christians can deepen the level of communion existing among themselves, and so they are to be considered an important part of ecumenical cooperation."