Acts 18:4 "EVERY Sabbath" both Jews and gentiles gathered in the synagogue to hear Gospel preaching - and as they heard they were believing -- yet still meeting "every Sabbath".
Yes, and what were the uncircumcised taught there?
Noachide law..As sons of Noah
Ac 15:20 But that we write unto them, that they abstain from pollutions of idols, and from fornication, and from things strangled, and from blood.
Or would you have us to believe that Gentiles (uncircumcised) were being taught to behave as Jew's there.
Do you find that challenge at the end of those texts that says "None of that is said in either OT or NT about 'week-day-1' " questionable?
The festival Sabbaths of unleavened bread
Ex 12:15
Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.
Ex 12:16 And in
the first day there shall be an holy convocation, and in the
seventh day there shall be an holy convocation to you;
no manner of work shall be done in them, save that which every man must eat, that only may be done of you.
1Co 5:8 Therefore
let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with
the unleavened bread of sincerity and truth.
The festival Sabbaths until Pentecost.
Ex 34:22 And thou shalt observe the
feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year’s end.
Ex 34:22 And thou shalt observe the feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year’s end.
Nu 28:26 Also in the day of the firstfruits, when ye bring a new meat offering unto the LORD,
after your weeks be out, ye shall have an holy convocation; ye shall do no servile work:
De 16:9
Seven weeks shalt thou number unto thee: begin to
number the seven weeks from such time as thou beginnest to put the sickle to the corn.
De 16:10 And thou shalt
keep the feast of weeks unto the LORD thy God with a tribute of a freewill offering of thine hand, which thou shalt give unto the LORD thy God, according as the LORD thy God hath blessed thee:
The festival period had its own days (Sabbaths) for rest...
The first day of the week of unleavened bread....Nisan 15
The first day of the week of weeks..... Nisan 16
So from the second day of the feast of unleavened bread ( after the "rest" of the first day) two weekly periods were running simultaneously. As well as two days of rest were being observed. The first day of unleavened bread, and the last day of unleavened bread.
Or would you have us believe Gentiles were being taught in the synagogue to eat the Passover uncircumcised?