It is extremely important that you share with us how you came to that conclusion of sabbath breaker is as guilty as a murderer.
If we are in danger of judgment I want to know so that I am not found guilty of disobeying God and the saturday sabbath.
Do you believe you should keep the 10 commandments?
Do you believe that all fall short ?
Do you believe that God forgives?
Do you believe that God knows what is in your heart?
Do you really need anything more than this to come to your decision regarding the Sabbath?
What I believe is of no consequence to you. It is what I believe what the Scriptures tell me. I am very comfortable with my decision on the 10. I am sure you will be able to decide for yourself whether you should honor The Sabbath or not. Remember, you have access to His Word and also to the Holy Spirit who will never steer you wrong.
But maybe you might do your own study on James 2:10-11 and perhaps other related verses. Best wishes…