Answer
In Hinduism, a guru is a personal spiritual teacher or guide. Though they are most often associated with Hinduism, gurus exist in the Buddhist, Jain, and Sikh traditions, too. The word guru means “dispeller of darkness” or “large, weighty, long, extended, important, prominent”; these definitions heavily play into the guru’s role as teacher.
Starting from at least 1000 BC, India has emphasized the importance of the tutorial method in religious teaching. Religious education in ancient India, and until the latter part of the twentieth century, consisted of oral transmission of the Vedas—the revealed scripture of Hinduism—from guru to pupil. Traditionally, the pupils, called shishya, live with their guru for a time and obediently serve him as he crafts instruction based on what the pupil must learn to advance spiritually. There is great importance placed on the lineage of teachers, called guru-shishya parampara. Generally, gurus are the former shishya of another guru in the same lineage.
In modern times, oral transmission is still highly valued, but gurus have written extensively on their teaching, and even give live or recorded lectures online, so they reach a much wider audience. Pupils are no longer required to meet gurus in person, let alone live with them. Hinduism can now be a pastime rather than an intense spiritual pursuit.
The job of a guru is to lead pupils on a spiritual path to help them attain “god” or realize their atman. Hindus hold that the atman is the eternal self, the spirit, or the essence of a person. On the path to liberation—also called moksha, nirvana, or self-realization—the final stage is realizing the atman is actually brahman, the one true reality and the force underlying all things. Hinduism states that a guru is necessary to reach such spiritual truths.
There is not really a biblical equivalent to the guru of Hinduism. Jesus told us to “make disciples” (Matthew 28:19), but the way to God is through Christ, not other teachers (John 14:6). Christians have one mediator before God: Jesus Christ (1 Timothy 2:5). Gurus in Hinduism each claim to be necessary to lead others to spiritual enlightenment, but Christians have the Bible, which is “profitable for teaching, for reproof, for correction, and for training in righteousness” (2 Timothy 3:16). We also have this promise: “You have received the Holy Spirit, and he lives within you, so you don’t need anyone to teach you what is true. For the Spirit teaches you everything you need to know, and what he teaches is true—it is not a lie” (1 John 2:27, NLT; cf. 1 Corinthians 2:12). And of course there’s a vast difference in the content of the teaching: gurus in Hinduism advise their pupils to look for divinity within; Christian teachers point to Christ, the divine Son of God.