When the gospel is at stake, everything is at stake.
If someone doesn't know their Old Testament, they don't know right doctrine, right correction, and they can't be equipped for good works.
My hopes of a future life are all founded upon the Gospel of Christ and I cannot cavil or quibble away... the whole tenor of His conduct by which He sometimes positively asserted and at others countenances His disciples in asserting that He was God.
The doctrine of Scripture teaches us about the authority of God's Word. Scripture must be the final rule of faith and practice for our lives. Not our feelings or emotions. Not signs or prophetic words or hunches.
The broader problem is that a great deal of popular preaching and teaching uses the bible as a pegboard on which to hang a fair bit of Christianized pop psychology or moralizing encouragement, with very little effort to teach the faithful, from the Bible, the massive doctrines of historic confessional Christianity.
Of all the doctrines of the Bible none is so offensive to human nature as the doctrine of God's sovereignty.
Jesus did not come to strike a balance between grace and truth. He brought the full measure of both.
I firmly believe people have hitherto been a great deal too much taken up about doctrine and far too little about practice. The word "doctrine," as used in the Bible, means teaching of duty, not theory.
The good word of the Lord with which we must nourish is the simple doctrine of the gospel. We need not fear either simplicity or repetition.
You might prove doctrine from the Bible till doomsday, and it would merely convince a people, but would not convert them. You might read the Bible from Genesis to Revelations, and prove every iota that you advance, and that alone would have no converting influence upon the people. Nothing short of a testimony by the power of the Holy Ghost would bring light and knowledge to them -- bring them in their hearts to repentance. Nothing short of that would ever do.
The word doctrine, as used in the Bible, means teaching of duty, not theory.
The New Testament writers did not invent a doctrine of Scripture they inherited it.
If men come among you who do NOT preach all the counsel of God, who do NOT preach of Christ, sin, holiness, of ruin, redemption, and regeneration, and do NOT preach of these things in a Scriptural way, you ought to cease to hear them.
Genuine Christianity is more than a relationship with Jesus, as expressed in personal piety, church attendance, Bible study, and works of charity. It is more than discipleship, more than believing a system of doctrines about God. Genuine Christianity is a way of seeing and comprehending all reality. It is a worldview.
To preach the gospel is to stae every doctrine contained in God's word, and to give every truth its proper prominence.