And he said, ‘The God of our ancestors has appointed you to know his will, to see the Righteous One, and to hear the words from his mouth, since you will be a witness for him to all people of what you have seen and heard.” Acts 22:14-15 CSB https://bible.com/bible/1713/act.22.14-15.CSB

Jesus, God our Lord, calls His people witnesses for the mission of every Christian, which is the Great Commission. To be effective and fervent witnesses, what do we need? We need the power and presence of His Holy Spirit, God in us, to form our behavior into His resemblance so that people see Jesus and experience Him from our acts of service. We also need the Holy Spirit to change our minds, which impacts our wills so that we think and speak as God thinks and speaks so that people may know the ways of God. The Holy Spirit works through the Word of God to reveal to us the will of God and the nature of God as recorded in the great works of God Scripture reveals. As we saturate our hearts and minds with God’s word, His Spirit speaks to us concerning particular applications for us to complete the good works He predestined us to accomplish. We can only know God’s will and see Him truly for Who He really is through His word. It is this word spoken into us to be accomplished by us that makes us effective witnesses of the life, death, and resurrection of Jesus. Our diligence to pursue God through Scripture has an equivocal effectiveness in our ability to be His witness in the world.