Pope Francis' encounter with a Lutheran community in Rome this weekend was his chance to advocate for greater unity among Christians, a theologian has reflected.

"He was urging that, if we share so much, we should be 'walking together' … and we should be impatient for unity, so that we can share the Eucharist," said Msgr. Paul McPartlan, the Carl J. Peter Professor of Systematic Theology and Ecumenism at the Catholic University of America.

"We mustn't just accept division and separation – it is not right that we should be divided, especially since we share one Baptism!" he told CNA in an e-mail interview.

The Pope visited the Lutheran community Nov. 15, celebrating vespers with them and delivering a homily. He also answered questions from three people while there. Much of his message focused on the points in common between Catholics and Lutherans, and on the aim of unity among Christians.

However, his response to Anke de Bernardinis, a Lutheran who is married to a Catholic, raised eyebrows in some circles. Anke, noting their happy and lengthy marriage and the regret of not being able to participate together in the Eucharist, asked, "What can we do to achieve, finally, communion on this point?"

The Pope responded at length, saying, "It's true that in a certain sense, to share means there aren't differences between us, that we have the same doctrine – underscoring that word, a difficult word to understand - but I ask myself: but don't we have the same Baptism? If we have the same Baptism, shouldn't we be walking together?" adding that when Anke and her husband pray together, their baptism "grows, becomes stronger."

He then said, "there are questions that, only if one is sincere with oneself and with the little theological light one has, must be responded to on one's own. See for yourself … To your question, I can only respond with a question: what can I do with my husband so that the Lord's Supper can accompany me on my way?"

"It's a problem each must answer, but a pastor-friend once told me: 'We believe that the Lord is present there, he is present. You all believe that the Lord is present. And so what's the difference?' - 'Eh, there are explanations, interpretations.' Life is bigger than explanations and interpretations. Always refer back to your baptism. 'One faith, one baptism, one Lord.' This is what Paul tells us, and then take the consequences from there. I wouldn't ever dare to allow this, because it's not my competence. One baptism, one Lord, one faith. Talk to the Lord and then go forward. I don't dare to say anything more."

Reflecting on the Pope's response to Anke, Msgr. McPartlan, who is a priest of the Archdiocese of Westminster, began by saying that "Pope Francis emphasized that he was NOT changing Church teaching on this issue, and he was deliberately very cautious in what he said. He stressed that he was not giving permission for anything."

The theologian noted five things which Pope Francis was doing in his reply: highlighting the commonality between Catholic and Lutherans; encouraging the two groups to walk together; responding from the heart as a pastor to a woman in distress; encouraging her to pray to the Lord; and "perhaps suggesting that particular theological and pastoral consideration be given to the circumstances of those Christians who belong to different churches but who are already united sacramentally in marriage."

First off, Msgr. McPartlan said, the Pope highlighted that Catholics and Lutherans "do share one Baptism, and many other common beliefs, so we mustn't just focus on what divides us," and he then called us to be "impatient for unity" and not to accept separation.

"He was responding from the heart, as a pastor, to the woman in her distress at not being able to share the Eucharist with her husband, and his wise reply was simply to pose a question for her to ask herself: 'What can I do with my husband so that the Lord's Supper can accompany me on my way?'"

The priest noted that "There are many possible answers to that question, depending on the actual circumstances of the couple, which we simply don't know."

"Do they both actually attend Mass regularly? If not, perhaps they could, and bring their longing to share the Eucharist to the Lord, even if they can't yet actually fully share in it. If they do, perhaps they could pray hard together, precisely at the Eucharist, for the reconciliation of their churches and offer their own pain and sacrifice at not sharing fully in the Eucharist for that cause."

He added that Francis "was urging her to pray to the Lord for guidance, and to act as she felt guided by the Lord, which is good advice always."

Finally, noting that "there are, already in the present rules, exceptional occasions when Eucharist can be shared" Pope Francis could have been suggesting that consideration be given to the circumstances of Christians who do not both belong to the Catholic Church, yet who are in a sacramental marriage, saying, "there are no particular provisions for them in the present guidelines."

"However, they are already 'one flesh' in the Lord, and already symbolise the unity between Christ and his body, the Church. If they actually live that mystery, which is so intimately related to the Eucharist, at a deep spiritual level – I'm speaking generally of married couples from different churches – then perhaps it would be appropriate for the Church to permit at least some occasions of Eucharistic sharing precisely on account of their marital union, because of the grace that is obtained there, a grace that would strengthen the couple for their special witness to the growing but not yet complete reconciliation of their respective churches."

Msgr. McPartlan also reflected at length on the Church's teaching and practice regarding the admission of non-Catholics to sacramental Communion.

He referred first to Unitatis redintegratio, Vatican II's decree on ecumenism, which said that sharing in the sacraments is not "a means to be used indiscriminately for the restoration of unity among Christians," based on two principles. First, the document notes, he said, that "sharing the sacraments expresses the unity of the Church, and that means that those who aren't united can't generally share the sacraments" and also that "the sacraments are means of grace."

Thus, Msgr. McPartlan said, "divided Christians can't generally share the sacraments, but there can be some exceptions on particular occasions, recognizing the need that people have and the grace that can be obtained through the sacraments."

He also referred to the "Ecumenical Directory", a 1993 document of the Pontifical Council for Promoting Christian Unity. He said that for a non-Catholic Christian of an ecclesial community to receive Communion (and other sacraments) from a Catholic priest, the directory gives three necessary conditions: that the person cannot approach a minister of their own community; that they ask for the sacrament on their own initiative; and that they manifest the Catholic faith in the sacrament, and are properly disposed – all of which is stated in the Church's law (CIC 844).

Canon law adds that this can be done in "danger of death or if, in the judgment of the diocesan Bishop or of the Bishops' Conference, there is some other grave and pressing need."

Msgr. McPartlan reflected that the Church's teaching on admission of non-Catholics to Communion derives from the Eucharist's place in the life of the Church, and its own reflection of the Church: "The word 'communion' itself conveys the link. The Church is a communion, and we receive communion in the Eucharist. It is therefore a contradiction for Christians to receive communion together in the Eucharist if they are not actually in communion with one another in the Church, because of divisions and doctrinal disputes."

"We can't be 'in communion' with others at the altar if we are not 'in communion' with them in terms of belief and charity in the Church at large."

He quoted from Ut unum sint, St. John Paul II's 1995 encyclical on commitment to ecumenism, which said that "there must never be a loss of appreciation for the ecclesiological implication of sharing in the sacraments, especially in the Holy Eucharist'."

The theologian reflected, "the hope of sharing Eucharist once again is precisely what drives ecumenical dialogue; we try to resolve the issues that divide us SO THAT we can share Eucharist once again."

"We are trying to re-establish 'full communion', and the prospect of sharing Eucharist again is a most powerful incentive to us to keep trying to overcome our divisions on serious issues of faith and order in the Church."