God is on a mission. God sent Jesus into the world on a mission and Jesus in turn sent His disciples into the world on a mission.
As You sent Me into the world, I also have sent them into the world. John 17:18
That mission, briefly put, was to make disciples, to transfer people from the kingdom of darkness to the kingdom of light. It is as simple as 1-2-3. The term "disciples" in the New Testament means learners. We who follow Christ are to be in a constant mode of learning.
Sanctify them in the truth; Thy word is truth. Jn 17:17
The purpose of studying the truth is to become Christ like. By learning the truth, not only are our faults and imperfections uncovered, but more importantly, we find power to change.
The purpose of responding to the truth or improving one's character is ultimately to speak the truth with credibility. Like Jesus and like those He commissioned, we are to inform others of the truth persuasively.
And for their sakes I sanctify Myself, that they themselves also may be sanctified in truth. Jn 17:19
The purpose of informing others or speaking the truth in love is to take the first step in fulfilling the Great Commission of our Lord Jesus Christ. This is the mission we have been called to fulfill.
"Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit, teaching them to observe all that I commanded you; and lo, I am with you always, even to the end of the age." Matthew 28:19-20