But you can't find any Scripture that so states. Okay.
Paul is saying NOTHING about Christians associating with others (congregations) or congregations associating with others (denominations). This you keep proving. He is denouncing theological division among CHRISTIANS. Yes, it IS wrong to be divided in doctrine but it's absurd to argue that every non-denom congregation fully and absolutely agrees with every other non-denom congregation on the planet on all matters. Indeed, a denomination holding all to the same faith probably leads to congregations agreeing more with others, not less. The 6000 congregations of my denomination are all in perfect agreement with the over 600 pages of our mutual statement of faith. Is your non-denom in equal agreement with over 6000 other non-denoms, on a statement at least 600 pages long ????? Yes or no?
Well, there may have been no denominations before the 4th Century, but that doesn't mean denominations are wrong anymore than books, Computers. Youth groups and youth pastors, Baptism tanks, Communion with little cut up pieces of Weber's White Bread and little plastic cups of Welch's Grape Juice, Altar calls, Catechisms, The Sinner's Prayer, Church websites, The internet, Forbidding those under the age of we-won't-tell-you from baptism, Christian discussion forums and a few thousand other things. Since you reject that we should do only as shown in the Bible (and not what is not) I agree with you and thus reject your entire point and premise here.
.