Archbishop Müller told the ordinariate leadership that they have the "delicate but all-important task" of preserving their communities' integrity while integrating them into "the larger Catholic community."
He stressed the need to foster a "culture of communion" with the bishops, the local dioceses and parishes, the Catholic faithful and "those still separated from the Church," an important task that requires "wisdom, humility, and a firmness of intention to avoid divisiveness."
The archbishop said that ordinariate communities will face "scrutiny" both from interested members of the Anglican Communion and from Catholics who "will want to know that you are here to stay, strengthening our ecclesial cohesion rather than setting yourselves apart as another divisive grouping within the Church."
He noted that members of the ordinariate have displayed "great courage" in entering full communion with the Catholic Church, and he continued them to continue exercising such courage.
At the same time, he warned against taking a "defensive or contentious" position towards Catholic Church authority, saying that "unity is easily undermined by a culture of suspicion."
"The openness of the wider Catholic community to the rich Anglican patrimony which you bring will be encouraged when they experience in your communities the joyful and peaceful embrace of our common faith," the archbishop said.
"In a world marked by division and discord, a culture of communion can be an especially eloquent witness to the truth of our faith and in fidelity to our Lord's prayer 'that they might be one.'"
Archbishop Müller also noted that the Holy Father has been heavily involved in the ordinariate, assuring its members that they "are very much in his thoughts and prayers."
Other featured speakers at the symposium were Cardinal Donald W. Wuerl of Washington, D.C., who had served as the Vatican delegate for establishing the ordinariate, and Monsignor Steve Lopes, an official at the Congregation for the Doctrine of the Faith.
Msgr. Jeffrey N. Steenson, who leads the ordinariate, also spoke, and Cardinal Daniel N. DiNardo of Galveston-Houston welcomed the attendees.