By far the most common theological system found today is Dispensationalism. This relatively new view (mid 1800's) is evolving so a definitive definition is difficult. However, it is possible to get a pretty good one as it is today from one of its major proponents. The following is his definition.

The essence of Dispensationalism, then, is the distinction between Israel and the Church. This grows out of the dispensationalists' consistent employment of normal or plain interpretation, and it reflects an understanding of the basic purpose of God in all His dealings with mankind as that of glorifying Himself through salvation and other purposes as well. -- Charles C. Ryrie, Dispensationalism Today