Enough of this tiresome matter!
Theology can and should do no more than advise the Church.
It would be as well for the Church, of course, if it would occasionally ask seriously for the advice of theologians, and if it would then listen to it no less seriously. In this matter of infant baptism, our advice has not been sought, and there is only the faintest hope that it will be heeded.
This advice cannot be that in its baptismal practice the Church should continue with a supposedly good conscience on the way which was entered in hoary antiquity and which has been obstinately pursued through all the vicissitudes of history. Theology cannot say to the Church that if it continues on this way it is acting in obedience and may thus have a good conscience. It cannot share with the Church the responsibility which the Church has taken on itself by introducing this practice, and which it constantly takes on itself by maintaining it. This practice is profoundly irregular. It is true that through the centuries and up to our own time the Church has not been destroyed by it (any more than by corrupt preaching or so many other corruptions). But it would be most dangerous-of all arguments for infant baptism this is the worst -to appeal to the fact, or to rely on it, that this practice will not harm it in the future. In the history of Israel the patience of God manifests its greatness and therewith also its limits in certain great judgments and disasters which were made unavoidable by the obstinacy of Israel. There can be no guarantee that a Church which is only too faithful to its ancient errors will for ever escape these.
To all concerned: to theologians, for unfortunately even theology has not yet realised by a long way that infant baptism is an ancient ecclesiastical error; to Christian congregations and their pastors; to Church leaders, presbyterial, synodal or episcopal; to all individual Christians, however simple, let it be said that they should see to it whether they can and will continue to bear responsibility for what has become the dominant baptismal practice, whether they might not and must not dare to face up to the wound from which the Church suffers at this genuinely vital point with its many-sided implications, whether they could not and should not undertake measures for its healing which do not bear the character of compromise, and which ought not, therefore, to be the last to call for consideration.
-- Karl Barth [Church Dogmatics IV.4, 'The Foundation of the Christian Life'] --
Now, at the beginning of the Church Dogmatics Barth writes rather beautifully about the ideal of 'theology in service'. The theologian can't help but be inspired by this romantic notion. I know that - for me at least - it's proved helpful in the construction of a theological vocation. And indeed it might well constitute what should be the case, in an ideal world. But (as we know) it's definitely not an 'ideal world' - and here Barth laments (with respect to Infant Baptism especially) that the Church has failed to listen. This is a frustration many theologians share - but are called to shrug off regardless, in our fighting the long defeat. Quite right. It's not as if theologians are always the innocent ones. (Read Helmut Thielicke's Little Exercise for Young Theologians for a deeply challenging description of why the modern Church might choose not to listen.)
Oh, and then there's Barth's stance on Infant Baptism. Well... that's a whole other subject I guess!!