The Apostles' presence in the synagogue on the Sabbath, (Acts 13:42-44) does not imply that Saturday remained the holy day for the Christian church. Instead, this passage reveals that the Apostles were preaching the gospel to the unconverted Jews and Gentiles. So it was by no means a Lords Day Church Service, that came on the following day.A scripture that does support sabbath keeping after the resurrection...
Act 13:42-44
42 And when the Jews were gone out of the synagogue, the Gentiles besought that these words might be preached to them the next sabbath. .....
44 And the next sabbath day came almost the whole city together to hear the word of God.
Act 17:2 And Paul, as his manner was, went in unto them, and three sabbath days reasoned with them out of the scriptures,
Act 18:4 And he reasoned in the synagogue every sabbath, and persuaded the Jews and the Greeks.
No verses that say they came together EVERY Sunday..
And... Jesus said.
Mat 24:19-21
19 And woe unto them that are with child, and to them that give suck in those days! 20 But pray ye that your flight be not in the winter, neither on the sabbath day: 21 For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.
Pray that you flight be not on the sabbath day.
"In those days" = Jesus is referring to both the destruction of Jerusalem and the final events, the end of the world.
Acts 17:2 does not teach that Paul was holding a Christian Lord’s Day Service on the Jewish Sabbath (Saturday). You have confused Pauls Outreach Ministry, with his Sunday Church Ministry.
The Bible is clear, the Christian Sabbath is Sunday. There is no way around that fact.
Acts 20:7 "Now on the first day of the week, when the disciples came together to break bread, Paul, ready to depart the next day, spoke to them and continued his message until midnight." This shows an explicit local church gathering for preaching and the Lord's Supper ("breaking bread") on the first day.
1 Corinthians 16:2 "On the first day of every week, each one of you should set aside a sum of money in keeping with his income. This is the regular collection as tied to the corporate worship assembly of the church.
Revelation 1:10 "On the Lord’s Day I was in the Spirit..." John uses a distinct new-covenant term (Kyriake hemera, Lord's Day) the first day of the week.
John 20:19 Christ appeared to the assembled disciples on the evening of that first resurrection day, establishing a pattern of meeting with His church on this day.
Just as the old Sabbath commemorated God finishing physical creation (Genesis 2:2-3), the Christian Sabbath commemorates the inauguration of the new creation via Christ's resurrection from the dead on the first day of the week.
In Matthew 24:19-21 Jesus was not teaching that Christians would be keeping a weekly seventh-day Sabbath during a future end-times tribulation; instead, He was warning His Jewish disciples about the practical and logistical difficulties of fleeing the impending destruction of Jerusalem in A.D. 70
Jesus mentioning the Sabbath (Matthew 24:20) addresses the reality that city gates would be closed, and traveling or fleeing would cause severe friction, hostility, or logistical blockades from strict unbelieving Jewish authorities and societal norms of that era.