The "8th day" theology is Gnostic Ogdoad... not Christian.
You are comparing the eighth day belief in the creation of man by a particular school of Gnostics, which warped Christianity, to the early Christian concept that Christ was risen on the eighth day - the completion of the world. That is, from the Jewish concept of ages and the days of the creation of the world, followed by its completion on the metaphorical 'eighth day', that is, the resurrection.
[/quote]"...The concept of an Ogdoad also appears in Gnostic systems of the early Christian era, and was further developed by the theologian Valentinus (ca. 160 AD)...." [Wikipedia, Ogdoad][/quote]
That's on wikipedia, yes. It doesn't relate here.
"...The Ogdoad, again, was shown as follows: They affirm that man was formed on the eighth day..." [Roman Catholic Fathers of the Church; Against Heresis (St. Ireneus); Book I, Chapter 18, section 2]
You can just say, Against Heresies. The belief that Christ was the eighth day or risen on the eighth day has nothing to do with the belief that man was created on the eighth day.
"...a work "On the Ogdoad", probably against the Ogdoad of Valentinus the Gnostic, written for the same priest Florinus, who had gone over to the sect of the Valentinians (fragment in Eusebius);..." [Roman Catholic Encyclopedia, section "I"; St. Irenaus]
Do you understand logic, or do you just make connections because one thing says a number and then you associate it with a totally different concept because it has the same number?
"...In the Epistle of Barnabas (xv) we read: "Wherefore, also, we keep the eight day..." [Roman Catholic Encyclopedia, section "S"; Sunday]
This 'Eighth day' is Gnostic.
What eighth day? The eighth day of Christ or the creation of people? Because those are two totally different things. Eight dollars is different than eight goats.
Why not say the '23rd' is a heretical concept? The 23rd what, exactly?
The Beast had seven heads and ten horns.
So is 'seven' and ten an evil number?
Is this SDA math-mythology? Just compare numbers until something lines up?