1st John 3:19-24 IF OUR HEART CONDEMN US Characteristics of those who are children of God walking in the light in fellowship with God and His people, are that they are committed to righteousness of life. They love others as a normal evidence of being indwelt by the Spirit of God, and thirdly they walk in truth. Loving others in truth, and righteousness are evidence of the new nature God has given us. The child of God who is sensitive to the truth of God may wonder if they are really in Christ because we so often fail. We miss opportunities to let our "light so shine before men," and sometimes we even do that which we know is wrong, or avoid doing what we know is right.
When that happens, our consciences bother us and we feel a sense of guilt to the extent we wonder if we have deceived ourselves into thinking we have been born of God. John addresses this matter of experimental evidence of walking in the truth of God. Emotions do have an effect on some people more than others so that they do not "feel" like they are doing what is right. They do not "feel the joy" of being a child of God. They "feel guilty" because they have not done enough or been openly committed enough to the Lord. Peter "wept bitterly" when he faced his failure of denying the Lord. He met the Lord personally after that and still had to face the fact of failure again.