Poussin shows St John baptising Christ on the banks of the Jordan River. The inclusion of ruins in the landscape was intended to evoke the antique world and give the scene an authentic setting. The theme of the Baptism of Christ had a long visual tradition, which Poussin would have known. In keeping with convention, all of the action centres upon the figure of Christ and St John, with the dove of the Holy Spirit hovering above, much to the astonishment of the three men on the far right. Baptism is the means by which a person enters the Christian faith, and it is the first sacrament that they receive. Through the act of baptism, Christians believe that a person begins their spiritual life and are adopted as children of God.