Complex sentence: Käsemann also began to take Jewish apocalypticism more seriously than most of his contemperary colleagues, and thought it to be of vital significance for a reading of Paul, and indeed famously described apocalypticism as "the mother of Christian theology".
Split into simpler sentences: Käsemann also began to take Jewish apocalypticism more seriously than most of his contemperary colleagues and thought it to be of vital significance for a reading of Paul. Indeed, he famously described apocalypticism as "the mother of Christian theology".