Indwelling sin in believers

From Triumph Over Temptation by John Owen as edited by James M. Houston:

Owen responds to Romans 7 as it discusses indwelling sin.

1. Indwelling sin is a law. "Worldly men, in spiritual and moral duties, act only according to this law and by this law. It is the ruling and prevailing principle in them affecting all moral actions with reference to a spiritual and eternal end."
2. Believers must personally discover indwelling sin.
3. Believers find this law present in them when they "would do good." "Grace has sovereignty in their lives...Thus a believer does not commit sin in a habitual and willful way. Grace enables him to have a constant and usually prevailing will of doing good.While the best a non-Christian can do is sin, the worst a Christian does is to sin."
4. Observe the state and activity of sin within believers. "When we realize a constant enemy of the soul abides within us, what diligence and watchfulness we should have!" (pages 42-45)