22 Hast thou faith? have it to thyself before God. Happy is he that condemneth not himself in that thing which he alloweth. 23 And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin. Romans 14:22-23
Often people with freedom like to show off that freedom to those who are strict. Paul forbids this. If your strong conscience allows you to eat meat or drink wine, don’t flaunt those things in front of those with a weak conscience. Also, those who are strict often like to “police” others to pressure them to be strict like them. But Paul says we are to keep these decisions between the Lord and us. “The faith that you have, keep between yourself and God.” This shows us again that the word faith in this passage is limited to faith in the realm of conscience. You are most certainly not supposed to keep your faith in the gospel “between yourself and God,” but spread that faith to everyone everywhere. But we are to keep our decisions of conscience between the Lord and us. Go ahead and use your freedom, but don’t flaunt it. Go ahead and be strict, but don’t expect others to be strict like you.
To live your life without faith in God is to live your life like an unbeliever. An unbeliever constantly sins against his conscience until it is seared. If you live this same way, you will destroy your heart. You are not the lord of your conscience; God is.
How do you know the difference between training your conscience and sinning against your conscience? You are sinning against your conscience when you believe your conscience is speaking correctly, but you still go against it. You are training your conscience when Christ teaches you through his scripture that your conscience has been wrong in a particular area, so you decide to not listen to your conscience in that one area. This is called adjusting your conscience, not sinning against it.