Sanders writes, "We must be careful to distinguish between 'human nature' and 'sinful nature.' They are not synonymous" (p. 112). He reinforces this point by reiterating that Jesus was fully human and yet without sin.
Being human is part of the original design that God declared good. Theologians have sometimes picked up on this theme and submitted that part of the sanctifying work in people's lives is not to make us less human (more "robotic"), but actually more human; more fully alive, with our emotions and intellect and all parts of ourselves being touched by God.
While it is obvious that part of being human is making mistakes, to say, "I'm only human" when we are faced with the fact that we have made bad choices or willfully disobeyed God or hurt another person, is probably a very poor way of avoiding responsibility for our actions, both naturally and supernaturally.
The fact is that our human nature is what God made us to be. It is good. So, attributing our sin to it is bad theology and anthropology. It quickly can become, God, why did you make me this way? Now, we have fallen into the same trap as Adam and Eve and every blamer and excuse maker in history. We actually dismiss our evil as God's fault.
However, we have a "satanic intrusion" (as Sanders describes it) that is our sinful nature. You may hear the apostle Paul talk about the sin living inside him or doing things he does not want to do (Romans 7), but you don't really hear the excuse from New Testament writers, "Well, I'm only human."
Knowing all of this doesn't solve much of anything for us. We are still left to wrestle with the reality that there is a force at work against us. Simply, we do sin in our humanity. The only point is to be careful what we believe as a result of that fact. We can quickly get into a pattern of all kinds of faulty thinking about God and ourselves if we are not careful to keep that distinction between the human and sinful natures that Sanders mentioned. Once those mindsets take hold, they distort the meaning, and reduce the power, of grace and mercy and love.
Sanders concedes that we are left with a mystery when we consider how we have two natures, and even more, how Christ depended on his anointing from the Spirit rather than his own deity for power in ministry (p. 114). It is mysterious, but it is extremely important and practical for us to realize this truth. Jesus did not have to escape His humanity to perform miracles or love perfectly. Neither do we have to escape ours!
No longer should we say, "I am only human" (insulting the Creator's craftmanship). Instead, we can say, "I am human enough to respond to God and submit to His Spirit and carry out His will today."