I also believe the Catholic Church contains the fullness of truth, but seeking to dialog with those of a different faith and learning about their viewpoints and faith experiences is not an act of heresy. Indeed, learning these viewpoints and weighing them against the truth we hold dear, may also strengthen our faith and enable us to understand more clearly the truth we proclaim as Christians. If one has a faith that is weak or wavering, then it is not a good idea to attend meetings where that faith is under attack or may be undermined, but a mature faith, firmly rooted in prayer and the sacraments, shouldn’t fear to expose itself to differing faiths or experiences. I live in a country where the number of Catholics is very small and it is impossible to avoid engaging with members of differing religions. It is important to recognize that attending a bible class in a Protestant church or attending a funeral service for a dear Buddhist friend in a Buddhist temple, is not an act of heresy, in spite of what Churchcamefirst says, but a means of dialog, evangelization, and of being a witness to that very truth we claim as our faith heritage.