That is what the Old Testament said, no debate there. But if you understand that in the New Testament, essentially a new covenant, after Christ died for us, we're to "love each other, as we do ourselves." Now, sins are still sins and the ultimate consequence for sin is death. Christ paid the price for it though, if you accept it. But if you don't accept it, you have to pay the penalty yourself. So in summary, Christ fulfilled the demand for guiltless blood to satisfy the Old Testament. Therefore we are to follow the New Testament.