The two fundamental affirmations of Christianity are that God is good, and that we are sinners. The two go together. It is tempting, however, to split them. Most people seem to quite like the first; even those who don't believe in God! It is the second that causes all the trouble. Some people don't know how to make it an affirmation; they only hear it as destructive and over time can't stop it demolishing their carefully constructed sense of self. Others embrace the appellation of 'sinner' because it fits their low sense of self. Just another way to flagellate themselves.
We can hide from the harshness of the designation 'sinner' by looking at 'sin' and 'sinner' as forensic terms, with the simple meaning that we fail. 'Sinner' becomes a bare fact, rather than saying something about our identity as human beings. As a purely forensic term it remains external to who we are. However, a more nuanced and deeper exploration of our failure makes us realise that everything we do is tainted: we are sinners, not just occasionally falling into sin. And this is when it start to gets harder and people are tempted to recoil from 'sinner' altogether. This rejection of 'sinner' is completely understandable if our sense of self is dependent on us creating our sense of worth, through a kind of moral standing. (I'm a good person, I'm worthwhile, etc.) The 'self-made man' remains in control, separate and ultimately alone. But must at all costs avoid anything that can tear down the self-creation. (Good people can occasionally sin, but they remain essentially good, i.e. I am good.))
The alternative is offered by the gospel. God loves us. God comes to us when we are sinners to show not only that we don't have to create ourselves, but also that we can gain our true identity in that relationship of love. Or to put it another way, when we are at our weakest God comes to us in an act of utter grace to show that we don't need to earn God's love. In Christ God's love is given freely and lavishly. And although grasping onto our self-creation will only hinder the full realisation of that love and our true identity in it, our self-creation can't prevent the generous showering of love that God gives to us. It can make us lovers of God and others. (Luke 7:47)
And we can go further than this. God's gracious act in Christ shows us that our self-creation remains irrelevant to receiving God's love. Grace is not a stepping stone to a spot where we can take over ourselves, eventually creating a self that doesn't need God entirely and utterly. We don't at some point take over from God's grace and do it ourselves and thereby eventually earn a grudging acceptance from God. Our identity is always to be found in God's gracious action in Christ.
Moralists are suspicious of the bold statement that our moral standing is irrelevant to receiving God's love. They are worried that grace then becomes cheap. St Paul's critics thought the same. Whatever you do with the call to holiness it should never be at the expense of our utter dependence on God's love irrespective of any self-created personhood or moral standing. On the other hand, St Paul did not preach cheap grace, and for all those who accept the pure gratuity of God's love an annual reading of Bonhoeffer on costly grace is a necessity. (Dietrich Bonhoeffer, The Cost of Discipleship, pp. 35-47.) Grace is not to be universalised as a principle that is everywhere present and automatically available apart from God's free act in Christ. This is the error of liberal Christianity: moving from God's love in Christ freely given and without reserve to a necessary principle universally available, conceived almost as a right. Cheap grace in other words.