What keeps people weak and ineffective in their faith toward God?

What keeps people weak and ineffective in their faith toward God?
Unconfessed sin plagues the conscience. Guilt feels like a heavy weight. Shame burns like fire.
  • “For when I kept silent, my bones wasted away
    through my groaning all day long.
    For day and night your hand was heavy upon me;
    my strength was dried up as by the heat of summer. Selah
    I acknowledged my sin to you,
    and I did not cover my iniquity;
    I said, ‘I will confess my transgressions to the LORD,’
    and you forgave the iniquity of my sin. Selah” (Ps 32:3-5).