Growing up Catholic, I was raised with the notion that the Roman Church was the holder of ultimate truth and that there was a certain infallible nature to the Church. All other traditions were wrong, confused, or flawed in some way. Perhaps it was a grave misunderstanding of Church teaching and doctrine, but I believed that the only to way to obtain truth was through the Church. Ecumenism and religious pluralism threatens this idea of the Church holding the truth. To think that truth can be held by other traditions (even a piece of it) is unfathomable to many conservative Catholics. This mentality can lead to a superiority complex among Catholics who feel that the Church is better than other traditions.
Catholic teaching is very black and white—what you see is what you get for the most part. Regardless of where one falls on the spectrum of obedience and agreement to Church doctrine, there is a clear set of teachings to grapple with. Teachings on sexuality and responsibility may seem outdated but at least one knows the official stance to support or rebel against. Religious pluralism threatens the control that the Church has over her members. By acknowledging pluralism, one acknowledges that there are truths and alternative means to obtain them outside of the Church. There is no control over how people think, what they do, or how they express themselves. It goes from being black and white to colorful which poses a threat to accountability to a set doctrine. I do not mean to describe the Church to be a power-hungry, tyrannical dictatorship needing to control every nanosecond of every life; however, obedience and loyalty to teaching is often emphasized and lack of conformity shunned upon. Individuals who seek to broaden their experience of the Divine by adopting practices from other traditions (even Christian ones) are often criticized by fellow Catholics who feel that if one sits when one is supposed to kneel or uses a mantra or acknowledges that Jesus was Jewish or discerns the possibility of entering another tradition because the Church is no longer home—one is deviant, ostracized, and shunned.
The Church needs to learn how to balance Catholic and catholic. There is a balance between being a universal church that is located in various parts of the world with being open to widening the circle of acceptance of individuals and beliefs that can broaden our understanding of God. Through the black and white (which brings order) God has been placed within the limitations of a box. I believe this unjustly binds the Almighty Creator of the Universe who is so much more than our imperfect minds can grasp. I find it problematic when people define God as this and not that or develop rubrics for what constitutes authentic religious expression—whatever does not conform to our labels/categories is some how less than and questioned.
The church is struggling to become comfortable with learning from other traditions. The Church is recognizing where she needs growth (at times admitting and owning errors and mistakes) and how religious pluralism can enrich liturgy, theology, and doctrine. It is a journey of discovering how to be catholic Catholics—why is that so scary?