In writing the Book of Acts, Luke traces the expansion of the Christian movement from its earliest beginnings to the time when it reached worldwide proportions. Luke was keenly aware of the way in which Christianity was being attacked by enemies of the movement, and he wanted to present the story of its development in a most favorable light. Although it was quite impossible to write a complete history of the movement, he selected those events that he regarded as the more important ones, sufficient to characterize the movement as a whole. Having been a companion of Paul, he was more familiar with Paul's work than he was with the activities of other Christian leaders. Then, too, he was an admirer of Paul and realized the significance of Paul's work in bringing the gospel to various cities. He deeply appreciated the points of view held by Jewish Christians, who conceived of Christianity as a further development of Judaism instead of as an entirely separate movement. He wanted to emphasize the agreements rather than the differences among those groups whose ideas frequently clashed with one another. In this respect, he was a kind of troubleshooter of the early Christian movement.
We do not know what source materials Luke used for writing Acts. Some things he observed himself, and quite possibly he may have kept a diary from which he extracted materials that were useful for his narrative. Presumably he had access to other manuscripts, and some of what he reported was obtained by direct conversation with others. Many things were omitted, and Luke was not completely unbiased in all that he wrote, but given these limitations, Luke produced a remarkable piece of work whose inclusion in the New Testament contributes a great deal toward a better understanding of the entire work.
The early Christian sermons that Luke summarized and recorded form to a very great extent the basis for a reconstruction of the kerygma, and from this point of view, the gospel records were made. Luke's account of how Christianity made its way among Gentiles without discarding the more vital points of Judaism did much toward establishing unity. The account of Paul's arrest in the city of Jerusalem and the trials that followed clearly vindicate Paul in the eyes of any impartial reader. The end of the book is somewhat disappointing because one would expect to read about Paul's trial in Caesar's court, but the account ends rather abruptly. Some people think that Luke intended to write a third volume of his history but was unable to do so. Of this we cannot be certain. However, we are indebted to Luke in no small measure for the two accounts of Christianity that he did write.
