Acts 23:1
"And Paul, earnestly beholding the council, said, Men and brethren, I have lived in all good conscience before God until this day."
Paul said, "I have lived in all good conscience..." That statement is a mouth full. To be able to say that you have a good conscience is to say that you have no skeletons in the closet that you are trying to hide. A good conscience is not what you portray to others, but knowing you've done right in private at all times.
Life is a compilation of actions, and your desire should be to make sure that each action is not one that you will regret later in life. This is what builds a good conscience. If you live your life in such a manner that you will have no regrets when you get old, then you will live your life with a good conscience. The Scriptures clearly show us how to keep a good conscience.
First, live in private as though God is with you in person at all times. I've always said that someone is watching you at all times. What you do in private will eventually come out. If you're going to keep a good conscience, you must live your life as if God is looking over your shoulder all the time, and He is. If you live this way, you will be sure to do right even when you are alone.
Second, you keep a good conscience if you treat God and man right all of the time. Acts 24:16 says, "And herein do I exercise myself, to have always a conscience void of offence toward God, and toward men." Is there someone who comes to mind that if they showed up you would avoid them because you've wronged them? Fear should not grip your heart if anyone were to walk into the room. Treat everyone right, and you will have a good conscience. Treat every person as if they were God, and you will be able to keep a good conscience.
Third, you keep a good conscience by being honest all of the time. 2 Corinthians 4:2 says, "But have renounced the hidden things of dishonesty, not walking in craftiness, nor handling the word of God deceitfully; but by manifestation of the truth commending ourselves to every man's conscience in the sight of God." Honesty is the key to keeping a good conscience. When someone goes around telling lies, they will have a hard time keeping a good conscience. Being honest is not just about telling the truth, but it is also being honest in your dealings with others. If you were dishonest in a business deal, then you are going to have a hard time having a good conscience. If you live a transparent life, then you will have an easy time keeping a good conscience.
Fourth, you keep a good conscience by praying for others. 2 Timothy 1:3 says, "I thank God, whom I serve from my forefathers with pure conscience, that without ceasing I have remembrance of thee in my prayers night and day;" Have you ever had that moment in life when you heard something happened to someone and you wished you had prayed for them? Praying for others keeps you from that moment. When you fill your life praying for the needs of others, then you will have no regrets when you see them.
Friend, one of the hardest things you will accomplish is keeping a good conscience. Don't live two lives, one in public and the other in private; instead, live one life all the time. Having a good walk with God and living as though you will always see someone again will help you to keep a good conscience. If there is someone you would not want to see at this moment, then I encourage you to get right with them so that you can keep a good conscience.