If Paul was not a Sabbath keeper then he was a liar.
In Acts 24:14 Paul states he†worshiped †the GOD of his fathers believing all things written in the law and the prophets.
In Acts 25:8 he stated he had "not offended the law of the Jews".
In Acts 28:17†he states "though I have committed nothing against the people or the customs of our fathers".
In Acts he was trying to prove to the zealous Jewish Christians that he was keeping the law.
"Do we make void the law through faith? God forbid: we establish the law". Romans 3:31.
There are no instructions in our Heavenly Father's word to rest, worship, keep Holy, or to celebrate the discovery of our Savior's empty tomb on the "first day of the week."
What you refuse to acknowledge is that the Law said it would end.
"Behold, days are coming," declares the LORD, "when I will make a new covenant with the house of Israel and with the house of Judah, not like the covenant which I made with their fathers in the day I took them by the hand to bring them out of the land of Egypt, My covenant which they broke, although I was a husband to them," declares the LORD. But this is the covenant which I will make with the house of Israel after those days," declares the LORD, "I will put My law within them and on their heart I will write it; and I will be their God, and they shall be My people. They will not teach again, each man his neighbor and each man his brother, saying, 'Know the LORD,' for they will all know Me, from the least of them to the greatest of them," declares the LORD, "for I will forgive their iniquity, and their sin I will remember no more"" (Jeremiah 31:31-34).
The writer of Hebrews commented at length on the passage in chapters 8 to 10.
"But now He has obtained a more excellent ministry, inasmuch as He is also Mediator of a better covenant, which was established on better promises. For if that first covenant had been faultless, then no place would have been sought for a second. Because finding fault with them, He says: "Behold, the days are coming, says the LORD, when I will make a new covenant with the house of Israel and with the house of Judah ... In that He says, "A new covenant," He has made the first obsolete. Now what is becoming obsolete and growing old is ready to vanish away." (Hebrews 8:6-8, 13).
Paul understood that God and His Law said it would change. That is why he could claim that he was supporting the law while pointing out that it concluded.
"It was for freedom that Christ set us free; therefore keep standing firm and do not be subject again to a yoke of slavery. Behold I, Paul, say to you that if you receive circumcision, Christ will be of no benefit to you. And I testify again to every man who receives circumcision, that he is under obligation to keep the whole Law. You have been severed from Christ, you who are seeking to be justified by law; you have fallen from grace" (Galatians 5:1-4).
"Therefore, my brethren, you also were made to die to the Law through the body of Christ, so that you might be joined to another, to Him who was raised from the dead, in order that we might bear fruit for God" (Romans 7:4).
"Some men came down from Judea and began teaching the brethren, "Unless you are circumcised according to the custom of Moses, you cannot be saved." And when Paul and Barnabas had great dissension and debate with them, the brethren determined that Paul and Barnabas and some others of them should go up to Jerusalem to the apostles and elders concerning this issue. Therefore, being sent on their way by the church, they were passing through both Phoenicia and Samaria, describing in detail the conversion of the Gentiles, and were bringing great joy to all the brethren. When they arrived at Jerusalem, they were received by the church and the apostles and the elders, and they reported all that God had done with them. But some of the sect of the Pharisees who had believed stood up, saying, "It is necessary to circumcise them and to direct them to observe the Law of Moses." (Acts 15:1-5).
After a discussion where it was proven that Gentiles were saved without following the Law of Moses, a letter was written:
"They wrote this letter by them: The apostles, the elders, and the brethren, To the brethren who are of the Gentiles in Antioch, Syria, and Cilicia: Greetings. Since we have heard that some who went out from us have troubled you with words, unsettling your souls, saying, "You must be circumcised and keep the law" --to whom we gave no such commandment" (Acts 15:23-24).
When Paul wrote to the Gentile brethren in Colossae, he told them:
"When you were dead in your transgressions and the uncircumcision of your flesh, He made you alive together with Him, having forgiven us all our transgressions, having canceled out the certificate of debt consisting of decrees against us, which was hostile to us; and He has taken it out of the way, having nailed it to the cross. When He had disarmed the rulers and authorities, He made a public display of them, having triumphed over them through Him. Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day -- things which are a mere shadow of what is to come; but the substance belongs to Christ" (Colossians 2:14-17).
The only deception I see taking place is taking only part of what Paul said out of its context and attempting to draw a conclusion different from what Paul actually stood for.
The Sabbath day was kept by resting. That was an Old Testament requirement to commemorate Israel's freedom from slavery. "Observe the sabbath day to keep it holy, as the LORD your God commanded you. Six days you shall labor and do all your work, but the seventh day is a sabbath of the LORD your God; in it you shall not do any work, you or your son or your daughter or your male servant or your female servant or your ox or your donkey or any of your cattle or your sojourner who stays with you, so that your male servant and your female servant may rest as well as you. You shall remember that you were a slave in the land of Egypt, and the LORD your God brought you out of there by a mighty hand and by an outstretched arm; therefore the LORD your God commanded you to observe the sabbath day" (Deuteronomy 5:12-15). This commemoration has no meaning for those who did not descend from Israel. In Christianity, worship is not done by resting.
Contrary to your assertion, worship was conducted on the first day of the week. "On the first day of the week, when we were gathered together to break bread, Paul began talking to them, intending to leave the next day, and he prolonged his message until midnight" (Acts 20:7). "Now concerning the collection for the saints, as I directed the churches of Galatia, so do you also. On the first day of every week each one of you is to put aside and save, as he may prosper, so that no collections be made when I come" (I Corinthians 16:1-2).