One of the great problems we have is the temptation to self-justification. But whenever we justify ourselves, it is because we are covering ourselves with stories and excuses, woven out of our own heads, instead of covering ourselves with the blood of Jesus Christ, plus nothing else.
Of course, the fact that we are sinners does not mean that we are guilty of every possible sin, and the Bible does teach us to resist false accusation. Job does this, the psalmist does it, and we are invited to do it. But we must not do this superficially, with the glib expectation that we are in the right because we are . . . us.
One of the great correctives against a self-justification that rings hollow is to grasp, truly grasp, the doctrine of original sin, or depravity. The Bible teaches that we are sinners by nature, objects of wrath by nature, and that the grace of God razed us to the foundations before starting over. And not only did God do this, He is still in the process of doing it. We are projects under construction, and rubble from the old house is still underfoot. This is why the self-justifying argument that leaps up in our throat whenever the first question is asked should be considered with a dubious eye.
The problem always starts with what we are, not with what we said or did. The solution always starts with what we are in Christ, and not with what we said or did. Remember who you were in Adam, and remember who you are in Christ. And with that fixed firmly in your heart, you may then explain yourself.