Hebrews 7:12-17, For the priesthood being changed, there is made of necessity a change also of the law. For he of whom these things are spoken pertaineth to another tribe, of which no man gave attendance at the altar. For it is evident that our Lord sprang out of Juda, of which tribe Moses spake nothing concerning priesthood. And it is yet far more evident: for that after the similitude of Melchizedec there ariseth another priest, Who is made, not after the law of a carnal commandment, but after the power of an endless life. For he testifieth, Thou art a priest for ever after the order of Melchizedec.
In Matthew 12, Jesus broke the sabbath again. He justified it by citing the example of David, how he ate the shewbread, which was not lawful for the common people to eat; and was blameless. And also how the priests in the temple violated the sabbath doing the work of the sanctuary and were blameless.
To Jesus, the priests doing the work of the sanctuary on a Saturday was a technical violation of the sabbath; but lo and behold, they were excused because of the temple: and Jesus is greater than the temple.
He has the power of an endless life. He is without sin in His nature and character. And therefore, the fact that He violated the letter of the sabbath day law does not mean in any way that He sinned. Jesus Himself was greater than the temple, He is the Son of God. Jesus Himself is the Lord of the sabbath day; that means He created it and is therefore not bound by it: and if He violated the letter of the sabbath day law it does not mean that His character and nature of perfect holiness was in any way compromised. The sabbath is an outward requirement; but its fulfillment in the New Testament is that it boils down to a relationship with the Lord (as an inward law). Jesus' relationship with the Father was perfect, and I am certain that He Himself esteemed every day alike (see Romans 14:5). The sabbath was fulfilled in Him in that He had a perfect relationship with the Father, not in the observing of a specific day. For what is the purpose of the sabbath? Is it not that we set aside time to spend sitting at the feet of Jesus to hear from Him in His word, resting from our labours just to sit at His feet? That good part will not be taken away from us. We are not cumbered about by many things as was Martha; but we have chosen that good part of sitting at the feet of Jesus hearing from Him. See Luke 10:38-42.
But if you believe that the letter of the sabbath day law is not a nonessential of the faith, then be fully convinced in your own mind. Believe it with all of your heart; and be sure to never even start up your car on any given Saturday; because that is kindling a fire.