Essential doctrines are principled, non-essentials are not.
Yes, that does require an explanation.
Isaiah 28:13 But the word of the Lord was unto them precept upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little; that they might go, and fall backward, and be broken, and snared, and taken.
1 Thessalonians 2:13 For this cause also thank we God without ceasing, because, when ye received the word of God which ye heard of us, ye received it not as the word of men, but as it is in truth, the word of God, which effectually worketh also in you that believe.
Principles direct right action, righteousness. The effectiveness of essential doctrines direct a life best suited to live with Christ. Non-essential doctrines have no effect on your salvation or your relationship with Christ.
Understand also that these essential truths (doctrine) are supported by scripture and do not stand alone. Line upon line and precept upon precept, evidence that God told us what He was about to do so that we would recognize our Savior when He came.
Here are some basic primary doctrinal truths upon which your very salvation hangs.
God sent Jesus into the world.
Jesus is the Son of God.
Jesus lived a life without sin.
The atoning sacrifice of Jesus Christ satisfied God’s need for justice.
Jesus rose from the grave.
Jesus ascended to the right hand throne of God.
Everyone is subject to Jesus Christ, in that He alone judges the living and the dead.
By faith we are saved through grace, meaning that placing your faith in the atoning work of Jesus Christ alone saves you and not your works.
John 8:26 I have many things to say and to judge of you: but he that sent me is true; and I speak to the world those things which I have heard of him.
You must believe Him.