1 Cor 16:2 shows that the early Christians were meeting on Sunday.
Justin Martyr, an early church father (l05-165 A. D.) wrote, And on the day called Sunday all who live in the city or in the country gather together to one place and the memoirs of the apostles or the writings of the prophets are read, as long as time permits; then, when the reader has ceased, the president verbally instructs and exhorts to the imitation of these good things. Then we all rise together and pray, and as we before said, when our prayer is ended, bread and wine and water are brought, and the president in like manner offers prayers and thanksgivings according to his ability and the people assent saying Amen.
>> “1 Cor 16:2 shows that the early Christians were meeting on Sunday.” <<
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Actually, it does the opposite!
It proves that the first day of the week was a work day, where it was acceptable to gather up one’s goods for offering. That could not be done on a day of worship and rest.