He has revealed to mankind who he is. This definitive self-revelation of God is the fundamental reason why the Church is missionary by her very nature. She cannot do other than proclaim the Gospel, that is, the fullness of the truth which God has enabled us to know about himself. Christ is the one mediator between God and mankind: “For there is one God, and there is one mediator between God and men, the man Christ Jesus, who gave himself as a ransom for all, the testimony to which was borne at the