not trying to push any doctrine here. just quoting in order to establish the truth about what Christians believed prior to the Nicene council:
If, therefore, those who were brought up in the ancient order of things have come to the possession of a new hope, no longer observing the Sabbath, but living in the observance of the Lord's Day, on which also our life has sprung up again by Him and by His death-whom some deny, by which mystery we have obtained faith, and therefore endure, that we may be found the disciples of Jesus Christ, our only Master-how shall we be able to live apart from Him, whose disciples the prophets themselves in the Spirit did wait for Him as their Teacher? And therefore He whom they rightly waited for, being come, raised them from the dead. If, then, those who were conversant with the ancient Scriptures came to newness of hope, expecting the coming of Christ, as the Lord teaches us when He says, "If ye had believed Moses, ye would have believed Me, for he wrote of Me; " and again, "Your father Abraham rejoiced to see My day, and he saw it, and was glad; for before Abraham was, I am; " how shall we be able to live without Him? The prophets were His servants, and foresaw Him by the Spirit, and waited for Him as their Teacher, and expected Him as their Lord and Saviour, saying, "He will come and save us." Let us therefore no longer keep the Sabbath after the Jewish manner, and rejoice in days of idleness; for "he that does not work, let him not eat." For say the [holy] oracles, "In the sweat of thy face shalt thou eat thy bread." But let every one of you keep the Sabbath after a spiritual manner, rejoicing in meditation on the law, not in relaxation of the body, admiring the workmanship of God, and not eating things prepared the day before, nor using lukewarm drinks, and walking within a prescribed space, nor finding delight in dancing and plaudits which have no sense in them. And after the observance of the Sabbath, let every friend of Christ keep the Lord's Day as a festival, the resurrection-day, the queen and chief of all the days [of the week]. Looking forward to this, the prophet declared, "To the end, for the eighth day," on which our life both sprang up again, and the victory over death was obtained in Christ, whom the children of perdition, the enemies of the Saviour, deny, "whose god is their belly, who mind earthly things," who are "lovers of pleasure, and not lovers of God, having a form of godliness, but denying the power thereof." These make merchandise of Christ, corrupting His word, and giving up Jesus to sale: they are corrupters of women, and covetous of other men's possessions, swallowing up wealth insatiably; from whom may ye be delivered by the mercy of God through our Lord Jesus Christ!
(Epistle of Ignatius to the Magnesians, Chapter IX) ~ 250AD