Slavery to freedom by means of instruction. And the thanks for that belongs only to God, through Christ.
Every person who has ever been born alive, was born into sin, because of the inherited Adams original sin, and then became chained to sin as a slave by means of individual decisions to commit sins.
The word for servant, indicates a bondage, or an absolute slavery in which the slave has no say whatsoever, over his own life. And sin is a harsh master, who would destroy you totally and completely without batting an eye.
Obedient from the heart, is a phrase that describes your initial decision to believe in Christ, which removed those chains of slavery from your life.
The standard of teaching, refers to instruction.
We all have to learn Bible doctrine, whether we admit it or not. But, through positive volition we decide to listen, and study, and learn. And that process further enhances our individual life, away from the drawbacks to our spiritual life that the sin nature tries to impose on us.
Delivered to you, is a reference to the instruction in Bible doctrine that you hear, when you are interested, and actively pursue on a day-to-day basis.
Christ went to the cross and did the work of salvation in our behalf.
We listen and learn of the gospel, and make a conscious decision to believe, which gains us our salvation, and ultimate freedom from sin.
But life does not end at the moment of salvation. It continues on, as does instruction on a daily basis, so that we can continue the completion process of our otherwise incomplete life.
Bible doctrine in the soul, is the foundation and building material for the completion of the structure of our soul.
Obedience from the heart, is our willingness to listen, and to learn, and therefore to advance within our spiritual life.
And in all of this, we have no credit to ourselves, but all the credit goes to God, in all aspects of the spiritual process, and our spiritual life.