Have Christians got exclusive knowledge about right and wrong? I think even a quick look at other religions and philosophies (even atheism) would suggest that we all share many beliefs about moral behaviour. Studies show that even babies react when they witness unfair or hurtful actions. So if all people have a knowledge of right and wrong, what difference does Christianity make? There are many answers to that, but here is just one.
Despite their knowledge about right and wrong, people often act unethically in order to get by, or to gain an advantage. No one except Jesus avoided this. However, Christian faith can improve the ability to carry out moral decisions. How does this happen? Well, "...faith is confidence in what we hope for and assurance about what we do not see" (Hebrews 11:1 NIV). We grow to believe that God will take care of our needs, safety, and purpose, which enables us to live with less fear*. And each time we experience God's provision of these things, our faith is reinforced. This enables Christians to rely more on God and less on themselves over time, and as a result to act with less fear and selfishness than they did before.
*So do not fear, for I am with you; do not be dismayed, for I am your God. I will strengthen you and help you; I will uphold you with my righteous right hand. Isaiah 41:10 NIV