Sin tempts us to flee from the presence of God. That's what Adam and Eve did in the garden (Genesis 3:8), and we do the same. But, of course, if God is God then we cannot escape his sight. Consider these texts:
Where shall I go from your Spirit? Or where shall I flee from your presence? (Psalm 139:70)
The spirit of man is the lamp of the LORD, searching all his innermost parts (Proverbs 20:27).
And no creature is hidden from his sight, but all are naked and exposed to the eyes of him to whom we must give account (Hebrews 4:13).
How can God's omnipresence affect our daily battle with sin? David Powlison writes:
Every time you remember that you are out in public, then you live an out-in-public life. “I AM WITH YOU” means you’re always out in public. In order to sin, you’ll have to drown out the voice of reality, put your fingers in your ears, and switch channels to the fantasy channel, the lie channel, the death channel. And even if you switch channels and sin by high-handed choice, you will still be in broad daylight before God’s searching eyes. You can shut your eyes and plug your ears, he’s still right here. You’ll never get away. And you only have to open your eyes, listen, and turn around in order to find help. After all, he who loves you says, “I am with you,” mainly to encourage you. (Excerpted from Making All Things New: Restoring Pure Joy to the Sexually Broken.)
For further reflection, see Ligonier's Devotional Living Coram Deo.