God made it
The seventh day was set aside for all mankind at Creation. After making the entire universe, God created the Sabbath by his own example of resting! He personally blessed it by giving it his undivided attention. This period is so important that it is the ONLY day in the Bible given a name (and not merely referred to by a number).
3. And God blessed the seventh day and sanctified it because on it He rested from all His work which God had created and made. (Genesis 2:3, Holy Bible - a Faithful Version throughout)
. . . but on the seventh day, the Sabbath, in it there shall be none. (Exodus 16:26)
It is the law
The Fourth Commandment, embedded at the heart of the Decalogue, specifies an exact period of time God commands humans to rest. The Ten Commandments were so important to God that he used his own finger to write them on tables of stone for the children of Israel!
10. But the seventh day is the Sabbath of the LORD your God. In it you shall not do any work . . . (Exodus 20:10)
Jesus kept it
Our Savior led a sinless life so that he could become the perfect sacrifice for our sins. He obeyed his Father in all things and kept all of his commandments. Jesus' custom throughout his life and ministry was to keep holy the Biblical period of rest (Luke 4:16). In fact, he not only kept it but also claimed he created it (Mark 2:28)!
The early church and Paul kept it
The apostles faithfully observed the seventh day rest from sunset Friday to sunset Saturday (see our article "Why Church on SUNDAY?" for more information). Rather than abandon the fourth commandment as some 'burden' believers no longer had to follow, the early church, especially the apostle Paul, regularly kept and preached on Saturday (Acts 13:14, see also 16:13 and 18:4).
Time is not lost
The integrity of the seven-day cycle has been preserved since the Eternal created the first week (Genesis 1 - 2). Regardless of the name given them in various cultures and languages over time, what we call Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday have remained in that order throughout history. This means that the seventh day God made holy at creation and confirmed in his commandments corresponds to our Saturday. For more information on this topic, please see our free article.
Adopted for non-Biblical reasons
Research reveals that the change from Saturday to Sunday did not come out of the Bible but was a post-apostolic tradition adopted by the church! The change was based entirely on the Roman Catholic Church's belief it had the authority, directly from God, to change the day of worship. According to the ground-breaking research, there are at least two major factors which led the Christian church to reject keeping the fourth commandment on Saturday and move toward worshipping God on Sunday.
"The first, anti-Judaism, which appears to have caused a widespread devaluation and repudiation of the Sabbath, thereby creating the exigency of a new day of worship. The second, the development of Sun-cults with the consequent enhancement of the day of the Sun over that of Saturn . . ." (Samuele Bacchiocchi, From Sabbath to Sunday, 1980, page 269)
"It appears that because of the exigency which arose to separate from the Jews and their Sabbath, Gentile Christians adopted the venerable day of the Sun (Sunday), since it provided an adequate time and symbolism to commemorate significant divine events . . . such as the creation of light and the resurrection of the Sun of Justice." (ibid, page 301)
It behooves those who consider themselves Christians to study the Sabbath in the Bible and examine the facts regarding Christianity's overwhelming acceptance of worshipping God on the day of the Sun (Sunday). In the end, it will all boil down to one simple question. Do you wish to keep the traditions of men or the words of God?