What is the “old sin nature”? Describe it.

The old sin nature is the source of sin within us, and like our fingerprints, each one is absolutely unique though all share the same basic structure. Every sin nature is composed of areas of weakness, where we are drawn to particular sins; areas of strength, where we are tempted to rely on our own good character rather than on God; areas of lust, which differ from person to person—some for money, some for power, some for fame, some for sex; and two basic trends, one toward asceticism, which leads to legalism, and one toward lasciviousness, which leads to lawlessness. One trend dominates and one is subordinate, and from these four elements an infinite variety of manifestations can come. Remember that even our strengths, apart from the control of the Holy Spirit, produce nothing acceptable to God, because "good" that does not recognize its need for God is evil.