Complex sentence: His 1960 doctorate at Basel with Oscar Cullmann and Karl Barth, on "Discipleship in Mark", convinced him that discipleship meant a radical project; consequently, he declined offers of university professorships and became a city missioner.
Split into simpler sentences: His 1960 doctorate at Basel with Oscar Cullmann and Karl Barth, on "Discipleship in Mark", convinced him that discipleship meant a radical project. Therefore he declined offers of university professorships and became a city missioner.