In 1644, a nonconformist congregation had been formed in the South Marsh district, between Spilsby and Boston, Lincolnshire, and one of its tenets was the rejection of sponsors in baptism.
Grantham's key convert was John Watts, a man of some property, who had received a university education, and became pastor of a baptist congregation meeting in his own house.
By the efforts of Grantham and his evangelists, a number of small congregations were formed in the south of Lincolnshire, holding Arminian sentiments, and so distinct from the Calvinistic Particular Baptists.
Grantham and Joseph Wright of Westby were admitted (26 July 1660) to present the "narrative" to Charles II, with a copy of the "brief confession" and a petition for toleration.
He was thrown into Lincoln gaol, and kept there some fifteen months, till at the spring assize of 1663 he and others were released, pursuant to a petition drawn up by him and presented to the king on 26 December.
[1] In 1666 Grantham became a "messenger," a position originally created by the older Baptists for the supervision of congregations in a district (cf.
The indulgence of 15 March 1672 did not meet the case of the Lincolnshire Baptists; accordingly, Grantham had another interview with the king on their behalf and obtained an ineffectual promise of redress.
With the established clergy of the city he was on better terms; John Connould, vicar of St. Stephen's, was a good friend, from a theological correspondence.
Yet he differed from the Anglican Arminians of his day in that he advocated more reformed doctrines of human depravity, the inability in spiritual matters apart from the convicting and prevenient grace of the Holy Spirit, penal substitutionary atonement, and justification by the imputed passive obedience and active obedience of Christ, as well as a more reformed view of sanctification.
Thus messengers engaged in evangelism, and apologetic activities, advising churches, mentoring and ordaining ministers, helping to resolve congregational conflicts.
His debates with Anglicans, Presbyterians, Quakers, and Roman Catholics were widely read and quoted in the seventeenth century and evinced his unique Arminian Baptist theology.
Grantham published:[1] Among his unpublished manuscripts were The Baptist's Complaints against the Persecuting Priests, 1685, and Christianitas Restaurata, of which the title seems borrowed from Servetus; both are quoted by Thomas Crosby for their biographical matter.