Meditation
Marcia Montenegro: “…Eastern and New-Age influences in our culture, the word meditation has come to mean a technique to enter another state of consciousness, to go beyond thinking, or to realize spiri­tual enlightenment. We cannot read these techniques and purposes into the Biblical word translated as meditation which originates from several different Hebrew words. The contexts of these words indicate an active pondering, thinking and learning, neither a technique nor a disengagement from the mind.
Winter 2005 MCOI Journal www.midwestoutreach.org

Breath Prayers
Richard Foster: "Christians ... have developed two fundamental expressions of Unceasing Prayer. The first ... is usually called aspiratory prayer or breath prayer. The most famous of the breath prayers is the Jesus Prayer. It is also possible to discover your own individual breath prayer.... Begin praying your breath prayer as often as possible."
Prayer: Finding the Heart's True Home, p. 122

Mantra
Ray Yungen: “Since mantras are central to New Age meditation, it is important to understand a proper definition of the word. The translation from Sanskrit is man, meaning to think and tra, meaning to be liberated from. Thus, the word literally means to escape from thought. By repeating the mantra, either out loud or silently, the word or phrase begins to lose any meaning it once had. The conscious thinking process is gradually tuned out until an altered state of consciousness is achieved.” http://www.lighthousetrailsresearch.com/meditationexcerptbyray.htm

Marcia Montenegro: “In Hinduism, Tibetan Buddhism, Transcendental Meditation, and sometimes in New-Age meditation, a word—called a man­tra—is given to the meditator to repeat. This is often the name of a deity, or sometimes a phrase meaning, “I am That,” “Not this, not that,” or simply, “I am.” The purpose of this mantra is self-purifi­cation, and to become open to spiritual truths.”
Winter 2005 MCOI Journal www.midwestoutreach.org

Gary Thomas: “Choose a word (Jesus or Father, for example) as a focus for contemplative prayer. Repeat the word silently in your mind for a set amount of time (say, twenty minutes) until your heart seems to be repeating the word by itself, just as naturally and involuntarily as breathing. But centering prayer is a contemplative act in which you don’t do anything; you’re simply resting in the presence of God.” Sacred Pathways, p. 185

Altered state/Alpha state
Richard Foster: "If you feel we live in a purely physical universe, you will view meditation as a good way to obtain a consistent alpha brain wave pattern" Celebration of Discipline, p.

Dr. Lee Warren: "Mystical states of consciousness happen in the alpha state ... The Alpha State also occurs voluntarily during light hypnosis, meditation, biofeedback, day dreaming, hypnogogic and hypnapompic states." , B.A., D.D.

Laurie Cabot: "The science of witchcraft is based upon our ability to enter altered states of consciousness we call "alpha"... This is a state associated with relaxation, meditation and dreaming...In alpha the mind opens up to non ordinary forms of communication...Here we also experience out-of-body sensations and psychokinesis and receive mystical, visionary information" Power Of the Witch, Delta Books, 1989

"Chanting or meditating silently on mantras helps one to attain an altered state of consciousness ..."
From an online encyclopedia of mysticism and the occult

True Self
Thomas Keating: “God and our true Self are not separate. Though we are not God, God and our true Self are the same thing.” Open Mind, Open Heart, p. 127.

Thomas Merton: “ex­ternal, everyday self….fabrication… our true self….is not easy to find. It is hidden in obscurity and ‘nothingness,’ at the center, where we are in direct depen­dence on God.”, Contemplative Prayer, p. 70.

Desert Fathers
The first appearance of something approximating contemplative prayer arises in the 4th century writings of the monk St. John Cassian, who wrote of a practice he learned from the Desert Fathers (specifically from Isaac). Cassian's writings remained influential until the medieval era, when monastic practice shifted from a mystical orientation to scholasticism. http://en.wikipedia.org/wiki/Centering_prayer

Centering Prayer is drawn from ancient prayer prac­tices of the Christian contemplative heritage, notably the Fathers and Mothers of the Desert, Lectio Divina, (praying the scriptures), The Cloud of Unknowing, St. John of the Cross and St. Teresa of Avila.
www.contemplativeoutreach.org

Christian meditation is often associated with prayer or scripture study. It is rooted in the Bible, which directs its readers to meditate. In Joshua 1:8, God commands his people to meditate on his word day and night to instill obedience. The psalmist says that "his delight is in the law of the Lord, and in his law he meditates day and night" (Psalm 1:2). The Bible mentions meditate or meditation twenty times.
http://en.wikipedia.org/wiki/Christian_meditation

Spiritual formation is the growth and development of the whole person by an intentional focus on one’s (1) spiritual and interior life, (2) interactions with others in ordinary life, and (3) the spiritual practices (prayer, the study of scripture, fasting simplicity, solitude, confession, worship, etc.)
.http://en.wikipedia.org/wiki/Spiritual%20formation

Silence: A silent mind, freed from the onslaught of thoughts and thought patterns, is both a goal and an important step in spiritual development. Inner silence is understood to bring one in contact with the divine or the ultimate reality of this moment. All religious traditions imply the importance of being quiet and still in mind and spirit for transformative and integral spiritual growth to occur.
http://en.wikipedia.org/wiki/Silence

Centering prayer is a popular method of contemplative prayer, placing a strong emphasis on interior silence.Contemplative Prayer: As it is expressed in a modern day movement is mystically (i.e. based on a technique or method) in which one empties the mind of thought through repetition, usually of a word or phrase or focus on the breath. In this case the silence would be an absence of thought, all thought.
http://www.lighthousetrailsresearch.com/

Mysticism is a belief in or the pursuit in the unification with the One or some other principle; the immediate consciousness of God; or the direct experience of religious truth. Mysticism is nearly universal and unites most religions in the quest for divinity. It can also be a sense of mystical knowledge. Dionysius the Areopagite was the first to introduce the concept "unknown knowing" to the Western World. In areas of the occult and psychic it denotes an additional domain of esoteric knowledge and paranormal communication. Even though it is thought that just monks and ascetics can become mystics, mysticism usually touches all people at least once in their lives.
http://www.themystica.com/mystica/articles/m/mysticism.html