By baptizing Jews, John drew the attention of the priests and Levites. Previously, only Gentile converts were baptized because they were unclean. By baptizing Jews, John was teaching that Jews also needed to be clean. Since the priests and Levites were responsible for keeping the Jews clean, a delegation was sent to determine who he was and what he was doing. Their curiosity of who John was focused on three possible answers, the Christ, Elijah or the Prophet.
The priests and Levites, who came to interrogate John, knew Scripture. When he quickly denied being the expected Christ, their attention turned to Elijah and the Prophet. The expected return of Elijah was based on Malachi 4:5-6. The last passage of the OT promised the return of Elijah, who would set everything right. The Prophet was promised in Deuteronomy 18:15-19. Based on the people's fear of God speaking directly to them in Exodus 20:18-20, God promised a prophet from among them who would speak for Him. God goes so far as to say He will personally deal with anyone who does not listen to this prophet.
To answer the question from the authorities of who he was, John quoted from Isaiah 40:3-5. But John did not quote the entire passage. He plainly stated he was the voice of the Isaiah passage who came to prepare the way of the LORD. However, he left off the conclusion, "The glory of the LORD will be revealed and people with see it".
The answer to why John was baptizing is found in John 1:31. He was baptizing with water so the One coming after him might be revealed. This One would also baptize, but with the Holy Spirit.
LORD God, thank You for Your Word. Thank You for grace upon grace. Thank You for revealing the Son of God not only to John but to me. Thank You for the right to become a child of Yours, born of Your will, not of my own or any other man.
"Behold, I am of small account; what shall I answer you? I lay my hand on my mouth." In Romans, the apostle Paul says the same should be true of all mankind. Romans 3:10-18 describes the condition of all humanity. Paul starts by saying "There is none righteous, no, not one; no one understands; no one seeks for God" and concludes with "There is no fear of God before their eyes." Then in Romans 3:19, he says that for those who understand, God’s law causes "every mouth to be stopped". God's questioning of Job has brought him to the same place. He realized the foolishness of questioning God because he does not understand nor can he explain the world in which he lives. God is so much greater and grander than His creation. If I cannot understand the "simple" things of His creation, why would I presume to question anything He chooses to do in my life?
Almighty God, creator of all I see and know, forgive me for placing myself in the position that You and You alone deserve. Forgive me for making myself a god and acting as if I was the one who knew and had authority. Thank You for forgiving my rebellion against You. I desire to be a faithful subject in Your glorious kingdom.