PC, you're right, and the argument your friends are using reflects a fundamental lack of understanding of both Buddhism and Christianity. They need to take the advice of the Dalai Lama who has frequently stated that the central doctrines of Buddhism and Christianity are not compatible and that one cannot be "a Buddhist Christian or a Christian Buddhist."
But to be fair, for those who are not well catechized, Buddhism is an easy trap to fall into because it does indeed appear to be very non-dogmatic and having little or nothing to do with religion; however, this is only true on the surface.
But let met stop here for the sake of those who aren't familiar with Buddhism to give some basic informatoin about the origins and teachings of this religion.
Buddhism began sometime between 400 or 500 BC with a man named Siddhartha Gautama who was the son of a king in India. He left his privileged life at the age of thirty to become an ascetic to travel and ponder the human condition - especially the reality of suffering. One day, while meditating beneath a bodhi tree, he became enlightened - thus becoming Buddha (which means "enlightened one") and afterward began to teach his dharma (doctrine) of the Four Noble Truths.
These four truths are: 1) life is suffering, 2) the cause of suffering is desire, 3) to be free from suffering we must detach from desire, and 4) the "eight-fold path" is the way to alleviate desire. The eight-fold path includes having right views, intentions, speech, actions, livelihood, effort, mindfulness and concentration. The final goal of Buddhism is not merely to eradicate desire, but to be free of suffering.
Northern Buddhism usually adheres to a pantheistic worldview while Southern Buddhism and schools like Zen Buddhism teach atheism. Buddhism may have some teachings that agree with Christianity such as some of the ethical teachings, but there are deep divides between the fundamental beliefs of Buddhists and those of Christians.
For instance, Buddhists do not believe in the existence of the soul. They believe people who think they have a soul are rooted in ignorance and in a desire to please one's "self" and that we become truly enlightened only after we come to the realization that there is no such thing as a soul. Christians not only believe in the existence of the soul, but that the soul can achieve eternal life through Jesus Christ. Buddhists believe in a reincarnation of sorts, but not of the soul. This reincarnation involves some element of one's former identity.
These are major differences, but they're only the tip of the iceburg.
Christians believe suffering brings us closer to God and unites us with our Suffering Lord. Buddhists believe suffering is something to be escaped from.
Christianity focuses on holiness, worship of God and restoring the relationship between God and man through Jesus Christ. Buddhists are not concerned with the existence of God but instead seek after "non-self" (anatman).
Christians believe that truth, and its Author, can be known rationally; Buddhism denies existential reality and believes nothing, not even the self can be proven to exist.
Christian prayer seeks to enter into a dialogue with God; Buddhist meditation strives to "wake" one from their delusions and to enter into altered states of consciousness.
Buddha's final words to his disciples were "Make of yourself a light. Rely upon yourself; do not rely upon anyone else. Make my teachings your light. Rely upon them; do not depend upon any other teaching." In other words, if someone is truly practicing Buddhism, they could not also be following Jesus Christ.
Because Buddhism (and other Eastern religious traditions) are made to appear innocuous by those who are attempting to sell these new trends to a Christian audience in the West, Pope John Paul II warned us about becoming involved in them. " . . .(I)t is not inappropriate to caution those Christians who enthusiastically welcome certain ideas originating in the religious traditions of the Far East - for example, techniques and methods of meditation and ascetical practice. . . In some quarters, these have become fashionable and are accepted rather uncritically."
For additional reading on this subject, see Catholicism and Buddhism by Anthony Clark and Carl Olson upon which this blog was based.
The Church document, Some Aspects of Christian Meditation is a fantastic source of information about the mystical differences between Christianity and Eastern Religions.
Many sections of the Pontifical document, Jesus Christ, the Bearer of the Water of Life, also deal with the differences between various Eastern religions and Christianity.
For a better understanding of the differences between Buddhist and Christian prayer, you may also want to read the book by Augustine Ichiro Okumura, OCD (served as consultor for the Pontifical Council on Inter-Religious Dialogue) entitled Awakening to Prayer which is available through ICS Publications in Washington DC.
Hope this helps. Good luck and rest assured, our prayers are with you!
Send your New Age question to email@example.com