Yes and no. Yes, if you desperately want to reach the world with the gospel. No, if you are not that desperate. Mark 16:15 is commonly called “the Great Commission,” and it tells us to “Go into all the world and preach the gospel to every creature.” The word “preach” means to “herald” with a raised voice. Not only did Jesus preach the gospel in the open air, but so did Paul, Stephen, Peter, Wesley, Whitefield, Spurgeon, and many others throughout Church history.
In fact, Charles Spurgeon, the Prince of Preachers, said, “No sort of defense is needed for preaching out-of-doors; but it would need very potent arguments to prove that a man had done his duty who has never preached beyond the walls of his meetinghouse.” John Wesley said, “What marvel the devil does not love field-preaching! Neither do I: I love a commodious room, a soft cushion, a handsome pulpit. But where is my zeal if I do not trample all these underfoot to save one more soul?”
When I witness one-to-one, I am excited that one person is listening to the words of everlasting life. In a good open air, I can witness one-to-two hundred. How much better it is to offer the cure to death and hell to two hundred than one dying sinner. I wish every Christian could say with the apostles, “We cannot but speak the things which we have seen and heard” (Acts 4:20), to a point where they would open-air preach to those unaware that they are on their way to hell.
Jonah 3:3 So Jonah arose and went to Nineveh, according to the word of the Lord. Now Nineveh was an exceedingly great city, a three-day journey in extent. 4 And Jonah began to enter the city on the first day’s walk. Then the cried out and said, “Yet forty days, and Nineveh shall be overthrown!”