Preaching on the streets is good. However, today, American evangelical preachers do not deal with the objections from the secular, from secular scientists, etc. The way they deal with them is sheer ignorance. They apply the notion: As long as I preached it from my mouth, I'm done. I did my duty.
Ultimately they gather themselves together, as a mean of maintaining their ego. Now their counterpart which sprung from the same evangelical background, also band up together with their own kind for the same reason.
The only way for evangelism to work under God, is via sacrifice. Sacrifice of ego. Not counting the opposing party complete folly.