Ontology is a branch of metaphysics that deals with the science of being. To be an ontological Christian is a way of saying that Christian is something that a person is. Baptism imparts a permanent supernatural character upon a person’s soul that marks him as a Christian. Someone who holds the beliefs that Christians hold but is unbaptized is a theological Christian (i.e., Christianity is a religion that he believes); someone who is baptized is an ontological Christian (i.e., he is a Christian). A person who is both baptized and a believer is both ontologically and theologically Christian.