Why do stories within the Old and New Testaments often conflict with one another?

The Hebrew texts tell about God primarily through the stories of the Abrahamic tribes, Hebrew people and the nation Israel. That God is known variously as Yahweh, El, El Shaddai and Adonai. The Hebrew texts were composed over a period of 700 years by numerous people, mostly anonymous, in several different literary styles (myth, history, song, wisdom, prophecy).

The pre-history found in Genesis seeks to explain the origins of the Hebrew tribes. Their actual history starts with the Exodus from Egypt. These are books about God, and as such they tell what people believed to be true. The stories conflict because people's experiences are always different, and because political considerations entered in.

To read the Hebrew Bible effectively, you need to step into it, try to understand why a story was being told, what encounter with the Divine had occurred, or what event in human history was being lifted up as revealing God. The story of Adam and Eve, therefore, isn't a literal account of human origins, but a way of expressing a later generation's understanding of why evil existed and what people meant to God and to each other.

The New Testament is similar, except that its focus is on Jesus of Nazareth and on the faith community that formed after Easter and Pentecost. In unique literary forms (gospels, epistles, apocalyptic) composed over a period of about 100 years, the New Testament seeks to communicate Jesus—his ministry, life, death and resurrection—and the work done in his name, and then to call the reader to faith in Jesus as Christ, Messiah, Son of God.

The four gospels offer four different, sometimes conflicting, perspectives on Jesus; the letters respond to specific issues of early Christian communities and therefore have their own diverse tone and content; and the apocalyptic (Revelation to John) dealt with persecution of early Christians.