So, we can look at our baptized children and plead with them in both word and by deed (godly example) to take hold of and recognize the beauty of the community of Christ so that they seek to take their place in the Body. We thus speak in an imperative tone to our children, saying, "Know the One in whose name you bear in baptism. Take hold! Profess with your mouth and believe in your heart that Christ is your Lord and Savior! Taste and see that the Lord is good! For if you do not flee from the name of Adam, you shall perish in Adam with all the more force of judgment. May your baptism be beautiful to you and not a terrifying sign of God's judgment upon your head." Meaning, don't trample upon the blood of Christ and make a mockery of it by rejecting the promises held out before you.
Furthermore, we preach essentially the same imperatives to those who have been baptized upon personal profession, the adult-baptized. The only distinction is that for someone baptized as a child, there should come a first-faith response as a result of receiving a steady diet of gospel preaching, which faith appears in the aftermath of the baptismal event. And for the the one baptized as an adult, his first-faith response yielding a profession of faith leads to his baptism.
In both cases, the same faith is nourished by the preaching of the gospel; the same
improvement of baptism is the duty of each baptized individual. We are to lay hold of Christ by the gospel which is set forth in signal form by baptism. The encouragement to persevere, the warning not to despise the meaning of baptism and the covenant it symbolizes, the hope of a full redemption promised by the sacrament--these are no less words to one of the baptized than to any another. Sacraments are for the strengthening of faith, so let us daily put on the dress of baptism (Gal.3:27), drink the drink of baptism (1Cor.12:13) and die the death of baptism (Rom.6:3-4).
Luther (I am reliably informed) advised a daily reflection on one's baptism, including a metaphysical drowning of the old man of sin. If baptism is just a personal declaration pertaining to my self-conscious embrace of new life in Christ through a public act that doubles as a social entry ritual to a community of professors, those who regard baptism thus tend to think of it more as a moment in time; not unlike a wedding event. A person gets baptized (wet) after the same manner he he gets wed.
It is preferable (following the metaphor) to think of baptism as a
state, much more than an
event; comparing it to
marriage rather than to the wedding. If in the married state, one may wake up to daily revel in the reality of that estate. One need not fantasize on reliving the ceremony (as nice as it may be to think back or look at the photos), but on the compelling facts of the hour and of recent experience and affirmations. One may daily repudiate the single estate, and vow to do nothing this day to annihilate the union, putting to death the old man, his habits, his liberties. The baptized person has the opportunity to daily do the same with regard to his spiritual estate.
The ceremony (to the wedded) or the sacrament (to the baptized) only marks an historic, public witness to claims made therein. They make formal, outward, legal unions (of various kinds), but they are designed to point to a greater or deeper reality of union, covenant, oneness, sharing, benefits, fruits, etc. In baptism God makes promises in Christ to his people. They are effective unto faith (and to none other); but even to those who once embrace them (superficially) and later reject them, they are genuine promises. There isn't anything fake about them, which is why apostasy is as equally real and terrible as covenant-abiding is real and joyful.
But let's be clear: neither an adult who turns away from his adult-baptism, or a covenant child who turns from his, ever had the vital union witnessed to by baptism. That's the tragedy. Nor is it the promise of God that has failed. It is not true that the sacrament of baptism creates vital union with Christ, or makes an infallible witness to such a thing already existing. Only in the case of the elect, it secretly (to men) but most certainly does indelibly claim those who have--or who will--believe the promise.
The sacrament of baptism is what the still-fallible church, limited as it is by an earthly condition, states in public on God's behalf: "I will be your God, and you will be my people; I will be God to you and to your children." The sacrament of baptism proclaims visible, administrative, legal union in this world, in the penultimate age before the end and before perfection and infallible clarity. Water baptism unites a person to the church, not to Christ; but it is Christ's church, his bride. If baptism by water is a bare sign, then a wedding with words and actions, signatures and even the ring itself, is a bare sign. What would render all that "bare signification" would be a sham marriage, no proof of marriage-reality manifested variously afterward, "till death do us part"
indeed.
Western culture has come to despise arranged marriages. I make no argument here for them, only it should be noted that no cultural practice for the creation of the estate of marriage is flawless, or has no obvious weaknesses. Arranged marriage of some kind was fairly common practice in ancient time, and is still practiced in some deeply traditional cultures. I mention the arranged marriage because by it a person could grow up into knowledge of and embrace of his/her betrothal culminating in marriage. So, any argument that the married-estate analogy doesn't work too well for the paedobaptist hasn't taken sufficient notice of ancient practices generally. It isn't the case that marriage has always been a purely individualistic, contractual, consensual arrangement. In any case, the two states in view here (baptism & marriage) are being analogically compared, not strictly paralleled as much as possible.
I want to end my comments where I began them. The faith-demand upon the baptized person is no different whether the person was baptized upon personal profession of faith, or presented for baptism by a professing believer parent (preferably two of them). There isn't one whit of distinction there,
unless one has set extra store by the initial, intelligent and robust commitment as the sure testimony of vital faith through which salvation comes. But isn't believing the same saving gospel a daily necessity thereafter? Don't Christians live and breathe on the gospel?
Salvation by grace through faith (the alone instrument) is the possession of every saint, who each without exception makes a transition from death to life; but the hour one first believed, forgotten by many if it was ever precisely known, is discounted (rightly so) in comparison to the question of whether I am at the present hour simply clinging to the cross, that implement being all I have ever known was able to save me to the uttermost. Believe in Christ who was baptized for his people, Lk.12:50, whose baptism yours is joined to (and is efficacious) if you believe its gospel witness.