It was Francis of Assisi who said, "Preach the Gospel at all times. When necessary use words."
Actually, that's not true. Francis never said it. Just as Marie Antoinette never said, "Let them eat cake." And Humphrey Bogart in the film Casablanca never said "Play it again Sam." Nor did Sherlock Holmes say, "Elementary my dear Watson". Not even close.
St Francis was not adverse to preaching. Neither was Jesus. Or Peter. Or Paul.
I suspect our reluctance to proclaim the gospel has more to do with doubt and fear than humility.
In Christianity Rediscovered, Father Vincent Donovan tells of his ministry to the Masai tribes of eastern Africa. Despite the establishment of schools, hospitals and other ministries, the Masai had not become Christians.
Donovan proposed to his bishop that he should distance himself from the services being provided to the Masai and “just go and talk to them about God and the Christian message.”
When he explained to one of the Masai elders what he proposed to do and why, his response was, “If that is why you came here, why did you wait so long to tell us about this?”