The Second Vatican Council encouraged theologians to draw on contemporary research in the sciences so as to help them to adequately communicate doctrine and recognized that this was necessary to keep pace with a rapidly evolving world. This was not viewed as impeding faith but rather catalyzing a “deeper and more accurate understanding of the faith.”[i] The recent Synod on Synodality understood itself as developing the potential of the Second Vatican Council.[ii] According to the Synod, it is the job of theologians to “help the People of God to develop an understanding of reality enlightened by Revelation.”[iii] One significant role of theologians today in a synodal church is to work in an interdisciplinary fashion so as to cross-fertilize insights from the theological tradition with contemporary science. An area in which this can fruitfully take place is in the area of the biology of sex, gender, and sexuality. In recent years, there has been an increasing number of theologians who are engaging in this area of biology.[iv] This paper will also contribute to an interdisciplinary conversation between theology and biology by looking at the 2019 Vatican document on gender theory. I will argue that this document nominally enlists biology to support some of its key positions but, because the document does not actually grapple with biological data, it misses the ways in which the data does not support these positions.
The essay will unfold in two parts. The first of these will briefly describe and unpack the importance of interdisciplinary research referred to by Pope Francis’ in his apostolic letter approving the new statutes for the Pontifical Academy of Theology. The second part will discuss two arguments from the 2019 Vatican document on gender theory and fruitfully bring them into conversation with relevant data from biological studies on sex, gender, and sexuality.
Key aspects of the first part: The value of interdisciplinary work was highlighted in Pope Francis’ apostolic letter approving the new statutes for the Pontifical Academy of Theology, published in 2023. This letter reflects Francis’ emphasis on the church as an outward-facing community of faith in a multicultural and multifaith world. Within this milieu, the church is called to cultivate a relational ethos of encounter, and a major part of this encounter is interdisciplinary research.[v] Such an engagement between theology and other disciplines has great potential to assist the faithful in coming to a deeper sense of the truths of faith and also to offer a compelling articulation of these truths for all who hunger for them.
Key aspects of the second part: The 2019 Vatican document entitled Male and Female He Created Them: Towards a Path of Dialogue on the Question of Gender Theory in Education (MFCT), refers to biology to support its views but does not actually cite any biological research.[vi] Without this research, theological views related to sex, gender, and sexuality (SGS) are reliant on an overly simplified understanding of reality, which neglects the synodal call for a deeper interdisciplinary engagement and hampers the truths of faith.
Some examples from MFCT illustrate the need for integrating theology and biology. The document makes the diagnosis that a central issue with contemporary gender theory is that SGS are conceptualized by a voluntarism in which the freedom of the individual outweighs considerations of female/male sex difference and complementarity.[vii] Yet, biological studies have demonstrated that biology can have a significant influence on sex (i.e. intersex conditions),[viii] gender identity,[ix] and sexuality.[x] While biology does not give a complete explanation for SGS, it does demonstrate that variations in SGS cannot be reduced to voluntaristic strains of thought in society. MFCT also states that when female or male sex is not clearly defined, “medical science should act with purely therapeutic ends, and intervene in the least invasive fashion, on the basis of objective parameters and with a view to establishing the person’s constitutive identity.”[xi] The directive given aims at establishing a definitive sex identity. However, when we consult biological studies on intersex conditions, it becomes clear that medical interventions cannot always inscribe such finality in the body.[xii]
The role of the theologian in a synodal church in the tradition of the Second Vatican Council is not to circumvent the complexities of the reality of bodies but to better understand them in a more nuanced theological anthropology through interdisciplinary research. This enriches the truths of the Christian faith and displays these truths in a compelling way to the contemporary world.
[i] Second Vatican Council, Gaudium et Spes, #62.
[ii] XVI Synod of Bishops, “For a Synodal Church: Communion, Participation, Mission,” #5.
[iii] XVI Synod of Bishops, “For a Synodal Church,” #67.
[iv] Examples include: Susannah Cornwall; Megan DeFranza; Megan Loumagne Ulishney; Craig Ford; Brianne Bell Jacobs
[v] Pope Francis, Ad Theologiam Promovendam, #4-5.
[vi] See Congregation for Catholic Education (CCE), Male and Female He Created Them: towards a path of dialogue on the question of gender theory in education (MFCT), #24.
[vii] See CCE, MFCT, #9-13.
[viii] Megan DeFranza, Sex Difference in Christian Theology: Male, Female, and Intersex in the Image of God, 23-46.
[ix] See Frederick L. Coolidge and Ari Stillman, "The strong heritability of gender dysphoria," in The Plasticity of Sex, 63-4. For example, Identical twin studies have found that about 38% of those assigned male at birth and 23% of those assigned female at birth experience GI when the other twin experiences it.
[x] See Jacques Balthazart, The Biology of Homosexuality, 143-4. For instance, twin studies have shown that, in both females and males, if one identical twin identifies as lesbian or gay, respectively, the other twin has about a 50% chance of experiencing that identity.
[xi] CCE, MFCT, #24.
[xii] For example, in a condition called 5α- Reductase Deficiency, major sexed features of the body change during puberty. See Richard Lippa, Gender, Nature, and Nurture, 124-5.
Theologians in a synodal church are called to engage in interdisciplinary dialogue, which was signaled by the Second Vatican Council. This paper explores how theologians can engage with the field of biology to provide the church with a more nuanced theological anthropology on sex, gender, and sexuality. The essay examines Pope Francis’ call for interdisciplinary scholarship, as emphasized in his 2023 apostolic letter to the Pontifical Academy of Theology. Then, this piece critically engages the 2019 Vatican document on gender theory, highlighting its reliance on biology to support theological claims while not actually incorporating biological research. By addressing intersex conditions, gender identity, and sexuality through both theological and scientific lenses, the essay argues that a more informed interdisciplinary approach is essential for theological anthropology. Such engagement not only deepens the church’s understanding of human identity but also strengthens its dialogue with contemporary society.