A guru is not necessarily limited to any one religion.
Hinduism has gurus, Sikhism has gurus, and the Russian Orthodox Church had gurus called staretz ... so gurus are something that goes across religious denominations. They are leaders, guardians and guides to people who seek the spiritual pathway through life.
Guru actually is a Sankrit word made up of two syllables, gu + ru
- gu means to sit near, to go near someone
- ru means to remove the darkness
So you would approach a guru seeking guidance, spiritual disciplines, perhaps a mantra, perhaps set activities in order to obtain spiritual progress.
Gurus also teach. The ancient system of education in India was called the gurukula system of eduction. There, the gurus taught by having their students answer their questions by themselves; by telling stories, using parables and metaphors.
Many gurus have seen, felt and experienced beyond the ordinary, everyday realms of life. Some live in communion with the Divine, moment by moment. Such gurus can, by a simple touch, grant the experience of the Divine to the seeker. The story of Swami Vivekananda is one example. His guru touched him on the head (in the region of what is called the Third Eye) and the young Vivekananda saw the unity of all existence; the experience lasted several days.
When a guru is selected, that guru may remain guiding the spiritual seeker, even when the seeker has gone away. In ancient India, there was a practice of live entombment of the guru, whereupon the Guru would retreat from the world, be sealed in a cave, and give energy and guidance to the spiritual seeker. This was called jivan-samadhi.
The Guru does not always need to come in actual concrete form; he can prompt the higher impulses and urges through a friend, or a book or an event which reveals the reality in a flash. After this, awakening, the rest is mostly in the hands of the aspirant. The Guru can always watch and guide. Spiritual seekers do not get agitated or lose heart. Spiritual seekers of a genuine guru are always guided, however far away they may be, geographically.
Religion means experience, so common sense has to apply if you are seeking a guru.
- Religion means experience and nothing less. We very often forget this important fact. This secret must be imprinted on the heart of everyone. Religious principles have to be practised and their validity experienced. Listening to their exposition is of no use; learning some one set of arguments and conclusions and repeating them parrot-like are not enough. If they appeal to one's intellect and are approved by it as correct, that will not help at all. It must transform.
A guru will transform you. Beware of false gurus.