Christian Kettler in his ‘The Vicarious Humanity of Christ and the Reality of Salvation’ has this to say about how ‘Vicariousness’ works in the Liberation Theology of Latin American theologian Leonardo Boff:
Christ is the absolute mediator, being both God and human (I Tim. 2:5) yet this absolute meditation does not rule out “the mediations of his
sisters and brothers. Rather it grants them, penetrates them, confers upon them their raison d’ Γͺtre.” The most immediate mediation in the light of Christ is that of the Blessed Virgin Mary. She answers the question “How does the feminine reveal God? And from the opposite direction, How is God revealed in the feminine?” As the “Mediator of All Graces” the mediation of Mary has, of course, been prominent in traditional Catholic theology. But because modernity has chosen to define itself as “logocentric”, i.e. “to assign primacy of the spirit to rationality and the power of ideas,” a profoundly masculinizing tendency, the feminine has become “marginalized” along with the distinctive traits of the feminine: “purity, self-sacrifice, and the protection of the weak and the oppressed.” Thus, the mediation of Mary becomes even more important today. Boff declares, “As we see it, each new generation finds itself in Mary, projecting its dreams, its social-cultural ideals upon her.” Today’s society finds Mary its “deliverance from the captivity of a political and economic system that exploits human work.” So Mary is the avenger of the weak and oppressed, although this must not be held in tension with the historical Mary, and particularly her humility. [Christian D. Kettler, “The Vicarious Humanity of Christ and the Reality of Salvation,” (Eugene, OR: Wipf and Stock Publishers, 2011), 34]
Aside from the obvious riff on the co-mediatrix of Mary; this makes for an interesting application of the doctrine of ‘Vicariousness’. In this scenario we have “social” categories predicating what humanity entails, and is characterized by. In other words, we have a doctrine of vicariousness that takes shape from ‘below’; so that what it means to be human (and female) is determined by the apparent attributes of what that looks like through the extension of that through female interaction with the world. While there are features of the female sex that are generally identifiable—like maternal, sensitive, compassionate, emotional, etc—these are not hard and fast characteristics. Ultimately, one of the problems with Boff’s proposal; is that its mode of operation moves from below. Humanity is actually given its raison d’ Γͺtre through the humanity of Jesus Christ (who is the imago Dei cf. Col. 1.15). There is no deficit in the reach of Christ’s humanity that needs to be augmented by a ‘feminine side’, like that puported by the analogy of Mary; NO! Mary’s humanity, like the rest of humanity, needs to be augmented by the humanity of Christ imago Christi.
This scenario helps, though, to illustrate the tension between trying to work out what being ‘human’ actually means in the first place; tension, between the Divine penetration of that in the hypostatic union of the eternal Logos with humanity (enhypostatic). In what way can we understand the Chalcedonian mantra of ‘distinct, but inseparably related’ (as to the natures of the person of Christ)? What does a theological (or christological) anthropology look like? And how would that implicate the vicarious humanity of Christ ‘for us’? The ‘for us’ is where I see the tension. How is the ‘us’ not swallowed up by ‘His’ humanity; and at the sameΒ time, how does ‘His’ humanity make ‘us’ who we are? Mary needed a recreated humanity as much as the rest of us (cf. I Tim. 2.5-6). There is just ‘One Mediator between God and humanity’; humanity remains my question.

