The believer caught between the flesh and Spirit is also caught between death and life. That is what happens when God intervenes in a human life. That intervention does not necessarily bring tranquility. In fact, it is more likely to bring tension and conflict. It is the life surrendered to the flesh which lacks inner conflict, for the decline through sin to death can be so easy. It is when the Spirit enters a life to contest the sway of sin and counter the weakness of the flesh that conflict ensues. The presence of moral conflict is a sign of the Spirit presence, not the Spirit's absence.
James D.G. Dunn, Romans: A Bible Commentary for Every Day
christianity, sin, spirit, the-flesh