The entire covenant given at Sinai to the Israelites was God's plan, in symbols, of His plan of Salvation which would be offered to the whole world at the coming of Christ. All these animal sacrifices, sacred feast days including the Sabbath, Passover and Day of Atonement, etc., were only shadows of the much more important reality which was to come, and that reality was Christ.
Col. 2:16,17 -- Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival (Passover, etc.) a new moon celebration or a Sabbath day. These are a shadow of the things which were to come; the reality, however, is found in Christ.
The Sabbath day was an important symbol -- a shadow of a thing which was to come. The shadow (Sabbath) with its weekly rest was pointing forward to Christ the Creator of the Sabbath. The Sabbath rest in the symbol, which was given only to the Israelites, was pointing forward to Christ who would offer His rest to all who would believe in Him and commit their lives to Him.
This rest, God's rest, was the rest that Christ entered into following His finished work of salvation at the cross. All born again Christians are invited by Him to join Him in that rest. This rest represents a complete rest from our works to achieve salvation. That has already been achieved by Christ and offered to those who believe, as a free gift.
Heb. 4:6,7 -- It still remains that some will enter that rest, and those who formerly had the gospel preached to them did not go in, because of their disobedience.
(These were the unbelieving Jews who heard the gospel preached by Christ but did not enter this rest that Christ offered. The weekly Sabbath rest they entered into religiously.)
Therefore God again set a certain day, calling it Today.
Vss 9,10 -- There remains then, a Sabbath rest for the people of God; for anyone who enters God's rest also rests from his own work, just as God did from his.
Heb. 3:12,13 -- See to it, brothers, that none of you has a sinful, unbelieving heart that turns away from the living God. But encourage one another daily, as long as it is called Today, so that none of you may be hardened by sin's deceitfulness.
This rest that Christ offers the born again Christian is a continuous rest in Him from His completed work for our salvation. The seventh-day rest in the shadow now becomes the continuous rest in Christ; today and every day as long as it is called Today. We now receive our salvation by faith as a promise by Christ to all those who believe. Christ places the Holy Spirit in our hearts as a guarantee that our inheritance is assured. This is the seal of the Living God. He takes charge of our lives and guides us in our every day walk with Christ.
That being said, I do not, in any way, condemn or think bad of anyone who chooses to keep the Sabbath. It is your God given right to be convinced in your own mind how to worship our all encompassing, awe-inspiring God.