Romans 7
20 Now if I do what I will not to do, it is no longer I who do it, but sin that dwells in me.

21 I find then a law, that evil is present with me, the one who wills to do good. 22 For I delight in the law of God according to the inward man. 23 But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members.

From Enduring Word Commentary:
There is a debate among Christians as to if Paul was a Christian during the experience he describes. Some look at his struggle with sin and believe that it must have been before he was born again. Others believe that he is just a Christian struggling with sin. In a sense this is an irrelevant question, for this is the struggle of anyone who tries to obey God in their own strength. This experience of struggle and defeat is something that a Christian may experience, but something that a non-Christian can only experience.

I love this thought. We are imperfect. Without a savior we cannot do it. We cannot serve Christ within our own strength.

Here is the same scripture in the message:
21-23 It happens so regularly that it’s predictable. The moment I decide to do good, sin is there to trip me up. I truly delight in God’s commands, but it’s pretty obvious that not all of me joins in that delight. Parts of me covertly rebel, and just when I least expect it, they take charge.