Overzealous evangelists have given preaching a bad name. That's why, when I edit articles about the Hare Krsna movement's attempts to spread the message of Lord Krsna, I routinely replace the word preach, in its various forms, with less loaded words. We generally don't like being preached to, and we don't like the idea of religious people berating others to change their ways or beliefs. The word preach has come to imply an over-the-top presentation that makes people uncomfortable.
Although Srila Prabhupada himself often used the word preach, he would also use teach, a much less intimidating word, and teaching is what he was encouraging his followers to do. Prabhupada called Krsna consciousness a science, and he wanted us to learn it and teach it. He was sure that if his disciples simply presented the wisdom of the Bhagavad-gita without change, intelligent people would be attracted to it.
Prabhupada sometimes used the discoveries of modern medical science as a metaphor for the imperative to spread Krsna consciousness. Someone who discovers the cure for a disease, he would say, doesn't hoard the information; he or she makes sure the whole world knows about it. Similarly, the world is suffering from "the material disease"lack of God consciousness and God's devotees are duty-bound to deliver the cure.
God Himself is the primary preacher. As the Bhagavad-gita tells us, Krsna and His representatives come to this world repeatedly with essentially the same message: Each of us is a spiritual being whose perfection, or salvation, lies in reestablishing our relationship with God, the supreme spiritual being. In fact, the material world itself is part of Krsna's "preaching program." He has created the world so that we will turn to Him after realizing the futility of trying to enjoy separately from Him.
No one pleases Krsna more than the devotee who assists Him in His mission of attracting the souls in this world back to Him and their eternal, spiritual home. Lord Krsna says that for one who teaches the Bhagavad-gita, "pure devotional service is guaranteed, and at the end he will come back to Me. There is no servant in this world more dear to Me than he, nor will there ever be one more dear."
Lord Krsna's most recent incarnation, Sri Caitanya Mahaprabhu, who appeared about five hundred years ago, is called the most merciful incarnation because He came to make love of God easily attainable. He was a preacher in the most admirable sense of the term. His heart overflowed with compassion for the suffering of the people of this age, and He brought the sure cure: the chanting of the names of God. The power of this spiritual medicine is unequalled. Srila Bhaktivinoda Thakura, a great spiritual master in the line of Lord Caitanya, has quoted Lord Caitanya in a song: "I have descended just to save you. Other than Myself, who else is your friend? I have brought the medicine for destroying illusion. Now pray for this Hare Krsna maha-mantra and take it."
When Lord Caitanya's followers assist Him in giving out the medicine of the holy names, they are not driven by a desire to recruit members to a sectarian religious faith. Rather, they are inspired by compassion for others and by a desire to please Lord Caitanya, who has appeared in this age out of His own infinite compassion.