If God didn't exist, or if God didn't care how we lived -- then you might be right. But God does exist and does care how we live -- and that makes all the difference!
In other words, guilt isn't something we just dream up, or feelings we get because we don't measure up to what others expect of us (although they may make us feel guilty). Guilt in the deepest sense comes from the knowledge that we have done wrong -- not just in the eyes of others, but in the eyes of God. The Bible says, "Whoever keeps the whole law and yet stumbles at just one point is guilty of breaking all of it" (James 2:10).
You see, God put within each of us a sense of right and wrong, and He also has told us in the Bible how we ought to live. Down inside we know it's wrong to hurt others, or to commit immorality, or to lie or cheat or steal. When we fail to meet God's moral standards, we feel guilty -- and we should, because we are guilty.
But God still loves us, in spite of our guilt! He loves us so much that He sent His only Son, Jesus Christ, from Heaven so we could be forgiven and cleansed of our sins. Don't be deceived; your guilt is real. But don't carry your burden of guilt any longer, but turn to Christ and open your heart and life to His cleansing power.