Rom. 14:23 But if people have doubts about whether they should eat something, they shouldn't eat it. They would be condemned for not acting in faith before God. If you do anything you believe is not right, you are sinning.
God dwells in every believer's heart through the Holy Spirit. The Spirit guides us into all truth, helps us to understand the truth, and empowers us to live the truth. He works within each of us in unique ways and we learn to apply truth within the context of our personalities and situations in life. There are many things we differ in because of our uniqueness. As long as we don't deviate from the truth of the Scriptures, it's okay to have different convictions about things.
We sin when we go against what the Spirit has convicted us of. If we sincerely believe something is wrong and we go ahead and do it, we sin. We are responsible for our own convictions. It doesn't matter whether or not someone else holds the same convictions that you do or not. Unless the Lord clearly shows you that what you are convinced of is wrong, you sin when you go against what you believe to be true.
We need to have a clear grasp on what we believe about things so that we will live it. We need to examine the Scriptures and ask the Lord to give us clear understanding of it. We need to ask the Lord then for the strength and willpower to live by our convictions. We must have a clear sense of right and wrong and live by it. God holds us accountable for the choices we make.