The various teachings of the Bible are merely aspects of that one doctrine. Doctrine can and should, at times, separate brethren from brethren, when some distort the truth to an intolerable degree. Doctrine certainly and infinitely separates brethren from unbelievers. We cannot accept what God hates. Doctrine, then, is the essence of our faith.
Love is a part of that doctrine.
Thus to really love God or others is to come to grips with doctrine - the whole counsel of God. We may only expand on what has already been given - there can be no extra revelations. There is only one 'doctrine' . In the Bible, the plural 'doctrines' is found only in the New Testament and it refers to false teachings or lies. When God speaks, what He says is automatically perfect and in harmony with everything else He has ever said.