john owen: the reality of sin's presence in doing good

There is no duty we perform for God that sin does not oppose.
And the more spirituality or holiness there is in what we do,
the greater is its enmity to it. Thus, those who seek the most
for God experience the strongest opposition.
~Sin and Temptation: The Challenge of Personal Godliness

For the desires of the flesh are against the Spirit, and the
desires of the Spirit are against the flesh, for these are
opposed to each other, to keep you from doing the things you
want to do. (Galatians 5:17)