An exceptional mathematician, Colenso was elected, in 1837, a fellow of St. John’s College, Cambridge and became an Anglican deacon in 1839.  He was heavily influenced in his religious views by his wife, Sarah Bunyon, who believed that God was present in all people at all times whether or they had ever heard of Jesus Christ.  This cleverly resolved the question of whether or not those who had never heard of Jesus whether because of where they lived or if they had lived before the time of Christ could enter Heaven. 

Upon marriage Colenso was appointed Rector of Forncett St. Mary’s Church, Norfolk in 1846 during which time he edited a missionary newspaper and so impressed Robert Gray, Bishop of Cape Town when he visited England that Colenso was offered position of the Bishop of the new diocese of Natal.  Consecrated in 1853 he subsequently made his first visit to his new diocese. On arrival, he divided his time between serving the English settlers and working with missionaries to the Zulus. The Zulu peoples had an enormous effect upon him and led him to challenge the Church’s teachings on treatment of the people of South Africa particularly on how converted polygamous men should behave.

On his return home, Colenso published ‘Ten Weeks in Natal’ and ‘The Proper Treatment of Polygamy’ causing huge controversy and accusations that he advocated polygamy. Returning to Natal in 1855, Colenso settled near Pietermaritzburg and he began to learn Zulu, wrote many articles, textbooks and translated the Bible into the main Zulu language, isiZulu.  He collaborated with many Zulu converts in order to adopt the correct meanings and idioms in the translation but this also led to many questions from the converts notably the truth or, perhaps lack of truth, in The Pentateuch (the first five books of the Old Testament).   

He was also personally challenged in reconciling Biblical truths with scientific discoveries and stated his doubt in the belief he been taught in childhood that ‘the Bible is none other than the word of God . . . absolute, faultless, unerring, supreme.’ doubts began to creep in.  He also discussed St Paul’s Epistle to the Romans and he compared the treatment of Jewish converts to Christianity with Zulu converts, insisting that the Zulus and the English settlers were of equal status and of equal value. In isiZulu, Colenso became known as ‘Sobantu’: ‘Father of the people’. 

In the 1879 Zulu Wars, Colenso supported the Zulus.  As a result, and with his wife’s continuing influence, he concluded that ‘the body and blood of Christ were given to all the human race, not only in the sacrament, but at all times’. He also came to doubt the accepted belief in eternal punishment. Attempts to force his resignation, stop his preaching and prevent publication of his works led to the first Lambeth Conference after Colenso was excommunicated. He appealed to the Privy Council arguing that he could only be removed by the Head of the Church of England i.e. Queen Victoria.  The Privy Council, acting on the monarch’s behalf, found in his favour.