Complex sentence: During the years 1656--57 Burrough and John Bunyan were engaged in a pamphlet debate, begun by Bunyan, who published "Some Gospel Truths Opened", in which he attacked Quaker beliefs.
Split into simpler sentences: During the years 1656-1657 Burrough and John Bunyan were engaged in a debate by way of pamphlets. First Bunyan published "Some Gospel Truths Opened" in which he attacked Quaker beliefs.