John was born on the 14th of August 1687 in Glenboig, Lanarkshire, Scotland to William Sloan  
(Clay Miner) and Agnes Clark. He started work at the early age of 12 in the mines of Glenboig, and  
had a somewhat rough existence there. Children were often employed in mines as 'pit drawers' or  
'trappers'. A drawer pulled the "whirleys' or carriages, and a trapper opened and shut the trap-doors  
for the ventilation.

Conversion - as told by John Clark Sloan
"On Monday night, the 29th August, 1892, with three companions, I walked into a tent in  
Glenboig, where Mr Martin, evangelist for the Lanarkshire Christian union, was conducting a  
Gospel service.  I was an unconverted and unconcerned sinner with no desire after higher  
things.  I took my seat along with my companions about the centre of the tent.  As I sat there I was  
not listening to the evangelist.  I did not even know what his text was;  my mind was busy with  
other things.  I was saying to myself, "What a fine twenty-four foot boxing ring this would make,"  
and so on.  I was startled by a lady rising to address the audience.  Part of her address laid hold  
of me.  She said, "All have sinned,"  "God is no respecter of persons,"  "The wages of sin is  
death,"  "The soul that sinneth, it shall die;"  then turning to where we were sitting she said,  
"Young man, though you have never drank a glass of whisky in your life, if you are not washed  
in the blood of Jesus, you are, so far as the fact of the guilt is concerned, on the same level as  
the worst drunkard that walks Argyle Street in Glasgow, for the Scripture saith, "Whosoever  
keepeth the whole law and offendeth in one point, he is guilty of all. The only difference is that  
you walk on the clean side of the road, and the poor drunkard travels on the dirty side;  but both  
are on the broad way that leads men away from God."  This was more than I had bargained for.   
It annoyed me that I should be compared with the worst drunkard, I, who was at that time Chief  
Ruler in the Rechabite Lodge. Besides I had a father who knew the evils of strong drink from  
experience, but who had been converted and had taught me to avoid liquor by taking me to the  
Band of Hope when I was five years old.  Then as I grew bigger he took me to the Good  
Templars, and now I was a leading light in the Rechabites.

All this, then, was more than my pride could endure, so I said to my chums, "I have had enough  
of this rubbish, let us clear out." As we passed out the door a man standing there added insult to  
injury by asking what I thought a very impertinent question.  He said, "Are you saved?"  Now, I  
hated those people who spoke about being saved, and pushing him roughly to the side I stepped  
out to the open air.  One of my companions said, "It is all right, don't trouble about that; every  
herring will have to hang by its own tail at the judgment."  But the Spirit of God laid hold of me,  
and in my soul I began to question if even I could be saved.  My sin there and then was brought  
home so vividly to me that I felt I was not fit to meet God.  Right there in the middle of the road I  
realised that I was nothing but a poor, lost sinner.  I turned and said, "If it is possible for God to  
save me I will be saved to-night."  I rushed back into the tent. The evangelist asked me what was  
the matter. I replied, "I am lost, sir; can you tell me how I can be saved?"  He said, "Hallelujah!"  
which only made me feel angry and miserable.  He took his Bible, sat down beside me, and drew  
my attention to Isaiah 1iii. 6.  He told me to go in at the one "all" and come out at the other, but I  
could not understand what he was driving at.  He then turned to John iii. 16.  At once I said "Sir,  
I know the Scripture as well as you; I learned it as a boy at Sunday School,"  but he said, "Have  
you put your own name into it?"  I said "No, and I would not like to do so."  "Why?" said he, I  
replied, "It would be presumption and nonsense."  The evangelist made answer, "you are neither  
an angel nor a devil; you are neither in heaven nor hell; you are here in this world; you are one  
of this world, for whom Christ died."  This seemed to be sound logic and satisfactory sense, so I  
put my own name in the verse and read it thus, "God so loved John Sloan that He gave His only  
begotten Son to die for him, that if John Sloan believeth in Him he should not perish, but have  
everlasting life."  The lovely light from above dawned upon my darkened mind and sin-blinded  
soul at that marvelous moment.  God had loved me, and Christ had died for me, and I should not  
perish but have everlasting life. Oh, the flood of glory that entered my soul!  I fell on my knees  
and thanked God with a full heart for sending Christ to die instead of me.  There in the attitude  
of prayer I yielded myself to Him who loved and died for me.  The evangelist didn't need to ask  
me if I was saved.  I jumped on to the platform and gave vent to my glad feelings by singing that  
hymn, "Oh, happy day, when Jesus washed my sins away."  Over thirteen years have rolled past  
since then, and to-day, if you ask me, "How do you know you are saved?"  my one answer is,   
"God says so, and I believe it."

In 1889 John married Isabella Black at Mollinsburn.  Isabella was born on the 11th of April 1864 to  
Matthew Black (Ironstone Miner) and Jane Black. Four children were born in Glenboig - Jane (Jean)  
1889, Agnes 1891, William 1892.  Agnes died at the age of three weeks from congestion of the  
lungs and William died in 1895 at the age of three from Diphtheria. John left his work in the mines  
around 1895 to begin his Evangelical work in Scotland and then to work as a Colporteur (Seller of  
religious books) in the Orkney and Shetland Islands and also in the islands of Norway. Isabella and  
their young family, Jean and Matthew accompanied John and they settled in Kirkwall, Orkney.  John  
received £50 per annum while working as a Colporteur. Two more children were born during their  
time in Kirkwall, John Clarke in 1897 and Isabella in 1899. In 1901 John and his family came to  
Australia. His passage to Australia was fully funded through the efforts of Mr. Andrew Stewart  
(Evangelist). John, Isabella and their four children arrived in Sydney on the 29th April. They then  
travelled with Mr Stewart to Brisbane, arriving on the Southern steamer on the 2nd of May. John  
continued his evangelical missions for the Presbyterian Church for approximately two years, then  
continued to do free lance evangelical work throughout Australia and the Commonwealth for many  
In December of 1928 John lost his wife of thirty-nine years. Isabella was of a very retiring nature, but  
deeply interested in the work of her husband and a lover of her home and family.

In the book on Andrew Stewart's life published after his death in 1952, he says of Mr. Sloan:
"The greatest pioneering work was accomplished by Jock Sloan, who evangelised in Queensland  
for fifty years.  In the first thirty years of work, he covered over a million miles, and wore out five  
motor cycles and nine motor cars! He travelled through trackless bushland, was caught in cloud  
bursts, 'bogged' in black mud, lost in sandstorms, was within an ace of death again and again,  
and brought thousands of men and women to the knowledge of Christ's redeeming love who  
might never have heard but for his courage, endurance and love.
Once when preaching outside a public house, the men told him to shut up.  He continued, so they  
tried to throw him in the creek, but he got away (he had been a boxer), and was back the next  
night preaching in the same place, and this time they let him alone.  He was like a bulldog for  
determination and loyalty."

John died at his home 'Mollinsburn' in Loch Street, West End, Brisbane on the 31st of July 1951.