While we can and may give some specific examples of how separating the first half of the Bible from the second half has lead to seriously misreading the later half (actually 30% of the Bible), the statement below is a broad stroke example of this error.
One confident evangelical theologian wrote, back in my seminary days, "For the Christian, the Law is a dead and a useless thing."  Really? Useless?
I recall the II Timothy 3:16-17 commentary on the OT scriptures is that all scripture is "profitable." "All scripture is God breathed and is useful for teaching, rebuking, correcting, and training in righteousness so that the man of God may be thoroughly equipped for every good work."
Psalm 1 says that blessed is the person who meditates on the law day and night. Paul in his inner man delights in the law (Romans 7).
Blessed, thoroughly equipped for ones life work…I could so easily go off on a diatribe. And there are those verses in the NT that seem less than complementary to the law and these deserve dialogue. Yet the bottom line is the First Testament is useful. It seems better to hear examples of how we have been blessed and equipped by the first half of the Bible (some 70% of the whole). How have you been instructed in your daily life, world view, and knowing God?
Consider yourself invited to share your examples as I plan to share ours.
Quoted T.M. Moore Celtic devotional Dec, 2009