“Preach the gospel always; if necessary use words.” St. Francis undoubtedly meant that you have to live the gospel, which is very true though his radical lifestyle would have really stood out. However, Francis was no Trappist (of course) and had plenty to say or we wouldn’t have so many of his quotes!
Today (amazingly) words are always necessary in proclaiming the gospel. I’ve met very nice and helpful Hindus and Buddhists. I’ve known Muslims who believe in being very moral and hospitable. So unless you tell people why you do what you do(and don’t do) they won’t necessarily know that you serve Jesus and that they can serve him too. However, words alone aren’t enough and can quickly lead to hypocrisy.