Acts 20:7 is an example of mistranslation of Greek to English. If you look at your Bible the word "first" was added to the verse. Words in Italics are not int the original text. If you look up the translation of the verse it says "the first sabbaton" was when they met together. That is the first of several Sabbath's in a row, probably the 7 weeks between First Fruits and Pentecost or the Feast of Weeks. There is another use of the same phrase that is used to fool people into thinking they met on Sunday. There is also a use of the word "Easter" in the KJV. It is clearly translated from the word "Passover" or Pascha in Greek.
The Apostles NEVER met on Sunday so the Scripture would say it,....not once!! They could have met on a Sunday, but that is NOT the Sabbath. They probably met on most days of the week.
The Pope changed to Easter, a pagan feast, from the Biblical command God gave His people. He likewise arbitrarily changed the Sabbath to Sunday,... the day they worshiped the Sun god. Tammuz (Nimrod's son) was born on Christmas or the winter solstice. Ezekiel 8:13-14 speaks on Tammuz and Ezekiel 8:16 speaks of a Sunrise Service as an abomination. It basically boils down to following God or a man. Does a Baptist or a Methodist know they are following a pope's decree to observe Easter? Jesus said many times that if you love Me you will follow my Commandments. What does the 4th Commandment say? God commanded us to observe the Feasts in Leviticus 23. The first one is the Sabbath. I could show you 15 more placed God said to keep the Sabbath holy, or set aside for God only.
You may have the opportunity to follow God or a man that claims to be God in the Tribulation. IMO, It's past time to get serious about learning how to follow the God of the Bible and reject false prophets. The reason for my post to the church seeker was to show him the Bible should be your "denomination". Follow the pattern of the First Church that Jesus started and reject the abomination men started.
As an example read 3John:9-10. John, the Apostle Jesus loved, asked to visit a Greek church to speak. Now keep in mind this is the John that actually walked with Jesus and the guy wouldn't receive him or John's followers. They were antisemitic. Antisemitism is the Spirit of Antichrist Jesus spoke of. Do you hate the family you were adopted into?
OK then.
Acts 15: the letter - what about it?