"Beloved, if our heart condemn us not, then have we confidence toward God. And whatsoever we ask, we receive of him, because we keep his commandments, and do those things that are pleasing in his sight." (1 John 3:21-22)
You can never get away with disobeying God.
Some people think they can. They think that if nobody finds out about it, it won't hurt anything. After all, God is merciful. He's not going to hold it against them, right? And if no one else knows...what's the difference?
What they don't realize is that their own hearts will start giving them problems. Their own hearts will start to condemn them. Everyone else may think they're great. They may be spouting faith talk all over the place, but when they come before God in prayer, they'll be filled with doubts and fears that keep their prayers from being answered.
That's one of the reasons why it's so important to live in obedience to the Lord. A life of obedience will give you a spiritual boldness you've never had before. It will give you a boldness in prayer, a boldness in faith. It will give you a confidence toward God, as the Apostle John says, that those who are trying to get away with sin don't have.
I'm not saying that you have to be perfect. That you must never make a mistake. But you should walk in obedience to the light you have. Take the time to listen and be responsive to the Spirit of God. When He tells you to do something, do it.
As you do, that confidence will rise up within you. It won't be something you mentally drummed up or talked yourself into. It will just be there. Instead of being consumed with doubts and feelings that the Word of God isn't going to work for you, you'll find yourself filled with faith that it will. You'll begin to trust God and to flow with Him. You'll come to a place the Bible calls "rest in the Lord."
Remember this: Even though the eternal price for your sins has been paid, a life of disobedience will still cost you dearly. It will cost you the boldness that is rightfully yours in Jesus. It will rob you of faith and rock you with fear.
Don't let the condemnation of your heart cut your confidence short. Do the things that are pleasing in God's sight and walk tall in the kingdom of God.