The idea of Inspiration means different things to different people. Some speak of gifted artists as being inspired. Some think of inspiration as a sudden or brilliant thought or solution. But these are not the idea Paul intends to convey in the text.
When Paul spoke of inspiration, he used a Greek compound meaning “God-breathed.” Paul believed that in reading the Scriptures, one should hear the voice of God as though God were speaking directly to him.
This is true not only of the New Testament but also of the Old. In the account of His temptation in the wilderness, Jesus quoted Moses from Deuteronomy when He said, “Man shall not live by bread alone, but by every word that proceeds from the mouth of God” (Matt 4:4, cf Deut 8:3). But inspiration does not make a text authoritative. The difficulty for many professed believers is not the idea that the Bible came from the mind and mouth of God. Rather, the problem is in determining which Scriptures are given for men today, the matter of authority.
Is man free to do or practice any Divine instruction he finds within the pages of Holy Writ? Is he permitted to piecemeal passages and construct his own religious faith and practice? The answer is no, although this seems to be common practice among religionists.
From the days of Sinai, God has given a body of instruction by which His people can know how to live and please Him. For Israel, that body of instruction is found in the Pentateuch, beginning with the Passover in Exodus 12, followed by the Ten Commandments in Exodus 20, and then the remainder of the Law of Moses.
But that covenant was only given for Israel and did not include the Gentiles (cf Deut 5:1-3). When God sent His Son, He established a new covenant (Heb 8) that includes all men, Jew and Gentile (cf Eph 2:11-22). Though all the Bible is inspired, only the New Covenant (or New Testament) is authoritative for men today.
The New Testament is the perfect law of liberty, and only those who continue in it will be blessed in their doings (James 1:25). To paraphrase Colossians 3:17, ‘Whatever you do in word or deed, do all by the authority of the Lord Jesus Christ.’ This means we must function within the scope of His authority as given in the New Covenant.