In Christian faith, theologians and philosophers make a distinction between: (a) preambles of faith and (b) articles of faith. The preambles include alleged truths contained in revelation which are nevertheless demonstrable by reason, e.g., the immortality of the soul, the existence of God. The articles of faith, on the other hand, contain truths that cannot be proven or reached by reason alone and presuppose the truths of the preambles, e.g., the Holy Trinity, is not demonstrable and presupposes the existence of God.