What is the scientific effectiveness of "street preaching" as a method of evangelization? I've been looking around for hard facts on the efficacy of street preaching but can't find any. Are there any hard numbers on the number of people who come to faith through this kind of evangelism? Has its efficacy changed over time? In Acts 2 Peter seems to use the same kind of technique with quite some effect. In my experience street preachers seem to be mostly met with either indifference or derision however that is entirely anecdotal.

So, scientifically, how effective is street preaching as a method evangelism?



Since I know of no studies I cannot define exactly what "efficacy" and other terms are in this instance, but I leave that to any studies if they exist.
In addition to Ken Graham’s excellent answer to this question, let me expand on the itinerant Protestant preachers who boldly declared the word of God in the open air, in fields and in public places, even when to do so would result in persecution.   From 1660 and the restoration of the English Monarchy, non-conformists were forbidden to preach anywhere unless they were ordained by an Anglican bishop.  John Bunyan, who wrote The Pilgrim’s Progress, was twice imprisoned for his failure to comply.  https://en.wikipedia.org/wiki/John_Bunyan#Imprisonment
Other Protestant preachers who engaged in open air preaching include:

John Wesley, founder of Methodism declared, &quot;I am well assured that I did far more good to my Lincolnshire parishioners by preaching three days on my father's tomb than I did by preaching three years in his pulpit ... To this day field preaching is a cross to me, but I know my commission and see no other way of preaching the gospel to every creature.&quot;


Wesley's contemporary, Anglican preacher George Whitefield stated: &quot;I believe I never was more acceptable to my Master than when I was standing to teach those hearers in the open fields ... I now preach to ten times more people than I should, if had been confined to the churches.&quot;


It was said that one of the regular practices of America evangelist Dwight L. Moody in the late 1860s &quot;was to exhort the passers-by in the evenings from the steps of the court house. Often these impromptu gathering drew as many hecklers as supporters.&quot;


Charles Spurgeon, the famous open-air Baptist preacher of England, believed that open-air preaching was instrumental in getting people to hear the gospel who might otherwise never hear it and many open-air preachers today believe that it reaches many more people at once than other approaches to evangelism do.


Groups such as Jehovah's Witnesses and Mormons are famous in particular for spreading their beliefs by door to door evangelism at people's homes, often in pairs or small groups.  Source: https://en.wikipedia.org/wiki/Approaches_to_evangelism

Back in the 1960’s Jehovah’s Witnesses expected their ‘Special Pioneers’ to spend 150 hours every month (1,800 hours a year) going from door to door, and ‘Regular Pioneers’ did 100 hours every month (1,200 hours a year).  A Jehovah’s Witness relative remembers engaging in street preaching back in the 1950’s, using placards and engaging in conversation with people in the High Street.
These days outdoor preaching, such as addressing crowds of people in parks or in other public places, seems to have ground to a halt because of the Covid pandemic.  However, the U.K. Baptist church I attend held “drive-in” services in the town centre public car park.  Anybody could turn up, sit in their vehicles with the windows down and hear the sermon and sing along to the hymns courtesy of a P.A. system.  Several visitors to the town and people who did not belong to our church stayed to listen.  There is no way to know whether anybody was converted to Christianity as a direct result, but historically many people have turned to Christ in faith after hearing the Gospel preached in some open-air or public venue.
What is the scientific effectiveness of street preaching as a method of evangelism?  Pew Research is my &quot;go-to&quot; source of information for statistics on Christianity, but I drew a blank on this one.  Back in the days of Bunyan, Wesley and Spurgeon, I doubt anybody stood with a note-book and pen to take names and addresses of people listening to an open-air preacher and then followed up six months later to enquire if said person was now a Christian.  Fast-forward to the 21st century and our age of digital data overload, legislation now exists to prevent proselytisers from recording personal details of people they contact.  Data protection legislation prohibits keeping such information on personal computers.
Some denominations keep detailed statistics on how much time they spend on speaking to members of the public outdoors, or speaking to them on their doorsteps, or how many pieces of literature they hand out.  They also keep statistics on how many people are baptised by them each year - although I have never seen any breakdown on how many baptisms were genuinely new converts as opposed to how many were brought up in that faith and were then baptised later in life.
I suppose an organisation such as Pew Research could poll Christians to ask if their conversion was a direct response to hearing a street preacher.  Whether that would be &quot;scientific&quot; or not I couldn't say.