I think one of the strongest arguments for paedobaptism is the practice of “baby dedication” that I’ve seen carried out in credobaptist churches. What’s the point of baby dedication, except to acknowledge that the child belongs to God in a special way not applicable to the children of unbelievers? And why invent such an extrabiblical practice except as an implicit recognition of the validity of paedobaptism?
Although the preaching of the Word is the principal means by which a child (or anyone) is brought to faith, baptism is also a means of grace, as are the prayers of the parents. Just as hearing the preaching of the Word does not assure salvation, neither does baptism nor prayer, but that does not mean they are useless or not means of grace.