Why is the New Testament considered a scripture?

Were the gospels considered scripture when the rest of the New Testament was written?

The confusing part of this question is that there was no "New Testament" until it was all written. And yes, when the canonical list of the New Testament books was compiled (a process that took about 400 years, although each book was written within the first 70 years), it was considered Scripture. Because they were considered scripture, they were locked up.

It is understood that the four Gospels, while only four of many, were the most popular four. Iraneus consists in Against theHeresies that there must be four:

The gospels could not possibly be more or less numerous than they are. Since there are four zones in the world in which we live and four major winds, while the Church is scattered all over the earth and the pillar and foundation of the Church is the gospel and the Spirit of life, it aptly has four pillars everywhere Exhale incorruptibility and revive men. It follows that the Word, the artisan of all things, revealed to men, gave us the gospel fourfold in form but held together by one Spirit.

That said, there were plenty to choose from. The four we have - Matthew, Mark, Luke, and John - were widely considered to be the best. Many others (Barnabas, Peter, Judas, Thomas) were either collected sayings or heretical Gnosticism. In addition, others, like Marcion, tried to make their own from scratch. Even so, these four have always been the most popular, profitable, best for censure, doctrine, etc.

Bruce Metzger argues that the symbolism might be more of an "afterthought" thing, but says:

"Among the small One of the [canonical] criteria that the ancients sometimes used was what can be termed 'number symbolism,' which we have striking examples of in Irenaeus and the Muratorian Canon ... It is no doubt true that this use of numbers was more common a symbolic interpretation of the facts after the settlement of the various parts of the canon as a means of determining that settlement. "(The New Testament Canon [New York: Oxford University Press, 1997], No. 5 at p. 254)

Time and again, the stories of these four Gospels came to the fore as the most important in attempting to accurately record how Christians should think and live.

Benjol

If you say the most profitable, am I assuming you mean the most edifying ...?

Affable geek

Yes - although I also alluded to 1 Timothy 3:16.