“All things are naked and opened unto the eyes of Him.” Hebrews 4:13
God knows all things that are, have been, and will be. There are no secrets from Him. Those things that we have kept from all others are not kept from Him. This is (and should be) both convicting and comforting. Convicting because our lives are an open book and “all our iniquities are set before Him” and comforting because those same sins He sees are paid for on the cross of Jesus Christ. How wonderful it is to know that He sees all we have done and will do, yet covers those sins with Christ’s blood.
Does that mean we can do anything we want? Does eternal security mean we have eternal license to sin? As Paul said, “God forbid.” Knowing that God sees all things and knowing that He sent Christ to atone for those sins should both convict and comfort. If we don’t live lives that show comfort and conviction, we should do one of two things. 
First, check our hearts to see if we have truly accepted the life, death, burial, and resurrection of Christ on our behalf. In other words, have we stepped from death to life by believing on The Lord Jesus Christ. If not, we need to do so, “for today is the appointed time.” If we have done that, but still lead a unconvicted, uncomforted life, we need to bring our lives into alignment with Him. If we don’t, we might still have eternal life, but we will not have a peaceful life and will have to face the natural consequences of our actions. Those who accept Christ and think they can live like the devil do not understand the wonderful eminence of God. God sits beside us, seeing, hearing, and knowing all we do- we might want to live that way.