Solus Christus

Solus Christus (Latin: "Christ alone"), sometimes referred to in the ablative case as Solo Christo ("by Christ alone"), is one of the five solas that summarise the Protestant Reformers' basic belief that salvation is through Christ alone and that Christ is the only mediator between God and man, see also New Covenant.

Protestant-Catholic relations
The doctrine was thought to be in contradistinction to several teachings of the Roman Catholic Church: the Pope as Christ's representative head of the Church on earth, the concept of meritorious works, and the idea of a treasury of the merits of saints. It is in some ways comparable to the church doctrine of Extra Ecclesiam Nulla Salus

A common Roman Catholic argument against Solus Christus is that Jesus needed to be born of a Mother, and that without the Theotokos, Jesus would have never existed (cf Mother of the Church, Annunciation and Incarnation).

As related to Soli Deo Gloria
Another criticism is that the doctrine is somewhat redundant to Soli Deo Gloria, since the divinity of Jesus has been acknowledged since before the time of the Apostolic Fathers and the Council of Nicaea.