1 Timothy 1:5 But the goal of our instruction is love from a pure heart and a good conscience and a sincere faith.
It is important to Paul that the teachers in his wake are pure doctrinally and spiritually. He give Timothy a specific template for dealing with those who are not. There teaching was likely disrupting the assemblies and causing some to loose faith. Paul then tells Timothy the real goal of our teaching.
First it is to be informed by love and faith. Paul often used these words in conjunction in the Pastoral Epistles. He wanted to make sure that those teaching in the churches he planted, and universally for that matter, were those who had a knowledge of the subject and lived according to their teaching. Taken separately, these two terms have great meaning in themselves. Especially when the adjective sincere is placed with faith. It is a faith that seeks only the truth and righteousness of God. Love can be seen to define the entirety of our goal for teaching; teach with love and all else will fall into place. We will not need to worry about our motive or lazy study if we act with love in our practices. Combined, these two words take on the meaning of St. Francis of Assisi's famous quote, "Preach the gospel at all times, if necessary use words." Paul intends for us to not just be "hearers." We must be the example of how the Word of God (and if we continue reading Timothy, the Law of God) is practical in our lives.
Second, our teaching/instruction (the NIV says command) is to be guided by a pure heart/good conscience. Again, the two phrases have great meaning apart from one another. Pure heart can mean sin cleansed or having a pure motive. To teach with a pure motive is quite important so we do not fall into the trap of being self-serving and out for personal gain alone. The "workman is deserving of his wages," but not at the expense of purity of content or growth of the student. Good conscience is used by Paul elsewhere to connote his own freedom from guilt over past sin. Together they have a greater meaning of one who has the cognitive grasp of his/her own salvation and subsequent freedom from sin and guilt. To be so, one must indeed have asked for that forgiveness and cleansing. Paul asserts then that a teacher must be one who is aware of his/her transition from sinner to saint. As one having a relationship with the giver of the Word and is the Word before attempting to instruct others in the meaning and application of said Word.
Paul's wish then is that instruction should come from a person who has been taught, seeks the truth always, endeavors to glorify God and see others grow while steering away from selfish motive, has asked for forgiveness and seeks to live according to his/her own teaching, does not fear the past in sin or guilt in rising to the challenge of a teacher, and is a continual learner themselves. See James 3:1
