Atheists choose 'de-baptism' to renounce childhood faith
While I imagine that "debaptism ceremonies" may be "therapeutic" for some (from their perspective) and perhaps a method of saying "in your face to the religious world" for others, when one considers the nature and application of the covenant sacrament and sign (i.e., baptism) one sees that those to whom the covenant and its sign is extended receive additional grace along with the responsibility to either accept and receive the covenant (and become recipients of its benefits) or to reject the covenant (whereby they not only forfeit the benefits but become accountable for unbelief and rebellion even in light of additional grace). For this reason, while some on the one hand may believe that by participating in a debaptism ceremony they are demonstrating they have nothing to do with the covenant/sacrament, on the other hand they actually demonstrate their participation by giving additional evidence of their rejection of the covenant,... and for this reason, as a Christian I'm not so much offended or taken back by their obstinance and rebellion, but saddened recognizing the gravity and future consequences if they choose not to repent. Recognizing and having experienced myself that God's grace is sufficient and abundant to exceed even our rebellion (Romans 5:10), I won't be surprised one day to hear testimonies of those who now participate in such ceremonies but live to recognize the waywardness and foolishness associated with it and go on to give God praise and glory for his saving them from such twisted thinking and corrupt practices and setting them apart as vessels for holy use.
Romans 5:10 "Romans 5:10 For if, when we were God's enemies, we were reconciled to him through the death of his Son, how much more, having been reconciled, shall we be saved through his life!"