There is no salvation without sacraments. The sacraments are saving powers, and not only strengthening powers, as in Protestantism. They have a hidden force of their own and to all those who do not resist grace they give this force. Baptism, confirmation, and ordination are of indelible character – this is against the Reformers, again. During your whole life you are baptised – and this had great practical consequences in the Middle Ages, namely, you fall under the law against heresy. If you were not baptised, you would fall under the law which limits strange religions as that of the Jews and the Islamic people and other people, and you wouldn’t be persecuted. But if you are baptised, you are a Christian and you can be persecuted by the law of heresy. Now here you see what such “indelible character” means. It is a life-and-death problem in the practice of the Roman church of that time. The same is true of the “indelible character” of ordination. It means that the excommunicated criminal priest, if he happens to marry somebody in prison – which happened often at that time – then they are married: the sacramental power in him overcomes his criminal situation and even his being excommunicated as an individual. If he marries you in prison, though excommunicated he still has the indelible sacramental power, which is always there and never can be taken from him. Here again you have a strong practical consequence of this doctrine of the “indelible character.” Now this, of course, stands against the Protestant doctrine of the universal priesthood. Not every Christian has the power to preach and to administer the sacraments, but only those who are ordained, and being ordained means having received sacramental power.
This sacramental power is even embodied in the ritual form of the sacraments. If there is a given ritual formula, no priest, no bishop, can transform it, can omit something from it, can change it, without sinning. The sacramental power is communicated from its origin in the actuality of the Church to the forms which are used – there is no arbitrariness possible.
Christianity, History of Christian Thought, Studies, Tillich