“All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work” (2 Timothy 3:16-17). When Paul wrote these words, the only Scripture that was available to the church was the Old Testament. For Paul then, the Old Testament Scriptures are profitable and enable the man of God to be trained and fully equipped for every good work.
I’ve noticed recently that a number of Christians when discussing Scripture seem to relegate the Old Testament as sub-standard. The law of God is particularly shunned. Comments like “I see you are quoting from the Old Testament, but we are New Testament Christians,” abound. It’s almost as though these people think Christ has done away with the Old Testament. These are our modern-day Marcions.
To respond, we must first of all look at how Jesus viewed the Law. In Matthew 5 in the Sermon on the Mount Jesus explains the Christian approach to the Law and the Prophets (the majority of the Old Testament.)
Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfil them. For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished. Therefore whoever relaxes one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever does them and teaches them will be called great in the kingdom of heaven. For I tell you, unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven.—Matthew 5:8-20