From: The Attributes of God, Vol. II

You may have been serving God quite a while, but instead of getting better, you feel you’re getting worse. You know what’s happening to you? You’re getting to know yourself better! There was a time when you didn’t know who you were and you thought you were pretty fine. Then, by the good grace of God, He showed you yourself - and it was shocking and disappointing to you. But don’t be discouraged, because He is faithful that calls you and He will also do it. God will finish the job.

1 Thessalonians 5:23-24 - Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ. He who calls you is faithful; he will surely do it.

Psalm 139:23-24
Search me, O God, and know my heart;
test me and know my anxious thoughts
See if there is any offensive way in me,
and lead me in the way everlasting.