Christian mysticism refers to the development of mystical practices and theory within Christianity. It has often been connected to mystical theology, especially in the Catholic and Eastern Orthodox traditions. The attributes and means by which Christian mysticism is studied and practiced are varied and range from ecstatic visions of the soul's mystical union with God to simple prayerful contemplation of Holy Scripture (i.e., Lectio Divina). This article addresses the practice of the inner, spiritual life within the Christian tradition.

As described by scholar Bernard McGinn, Christian mysticism would be "that part, or element, or Christian belief and practice that concerns the preparation for, the consciousness of, and the effect of [...] a direct and transformative presence of [the Christian] God". The idea of mystical realities has been widely held in Christianity since the second century AD, referring not simply to spiritual practices, but also to the belief that their rituals and even their scriptures have hidden ("mystical") meanings.