Luther On Infant Baptism

I still maintain, as I have maintained, that the surest Baptism is infant Baptism. For an old person may deceive, may come to Christ as a Judas and permit himself to be baptized. But a child cannot deceive. It comes to Christ in Baptism as John came to Him and as the little children were brought to Him, that His Word may come over them, touch them, and thus make them holy. For His Word and work cannot pass by without effect; and in Baptism they are directed at the child alone. If they were to fail of success here, they would have to be entire failures and useless means, which is impossible.

What Luther Says, 139 Baptism of Infants Surely Efficacious, p50. Emphasis mine.