In one of the episodes his ex-wife turns up and they spar in an ex-husband and wife sort of way before she explains why the marriage didn't work. She said that she just wanted to be with someone who didn't know every time she was lying, every time she was even moderately attracted to another man and every different emotion she felt.
I guess most of can empathise with this thought. It would be terrible if someone knew every lie we told, every emotion we felt etc. This is, however, what the Bible says that God can do. It says that God knows everything about us (see this for example) and can as such see every lie, every selfish thought or act, every wicked intention or desire. The amazing thing about God when compared to Cal Lightman is not only that he knows more but that despite all this knowledge he still loves you. God sees it all but still was willing to die for you so that you could find that forgiveness.
The fact that the idea of someone knowing you completely terrifies you shows your need of forgiveness. However, it is by asking this very same person to forgive you that it become possible to find forgiveness and a hope that one day you won't feel so ashamed!