Are the prophets still relevant?

What shall Christians do with the Old Testament, especially the prophets? May we quote them? There seems such a lot of negative words spoken by them which may offend today’s generation?

Let us read what Paul taught his disciple, young Timothy, a Spirit-filled Christian pastor/teacher in charge of a number of churches.

“You have been taught the holy Scriptures from childhood, and they have given you the wisdom to receive the salvation that comes by trusting in Christ Jesus.
All Scripture is inspired by God and is useful to teach us what is true and to make us realize what is wrong in our lives. It corrects us when we are wrong and teaches us to do what is right.” （2 Timothy 3:15-16)

Briefly I summarize below the keys Paul charged Timothy, and all Christians.

1. Paul spoke of the Holy Scriptures, which include both the Old Testament and the New Testament. The Scriptures gave Timothy wisdom to receive salvation by believing in Christ Jesus.
2. Paul also elaborated further. He declared that “all Scripture is inspired by God”. Here he does not differentiate between Old Testament and New Testament. In Paul’s days they had only the Old Testament and letters written by the apostles themselves to the churches. He was referring to the Old Testament mainly.
3. Paul declared that “All Scripture is inspired by God.” There is no dispute about the divine authority of the Scripture, Old (before Christ), and New (during and after Christ).
3. Paul taught that Scripture is relevant to Timothy, the New Testament Christian.
4. Paul taught Timothy the relevance of Scripture: “useful to teach us what is true and to make us realize what is wrong in our lives. It corrects us when we are wrong and teaches us to do what is right.”
5. All these are in present tenses. The power of the Scripture to change lives is alive today.
6. What does Old Testament do today when quoted? The same effect as declared above.
7. Were Old Testament verses quoted after Jesus ascended into heaven? Yes. In the first sermon given by Peter after he and 119 disciples were baptized by the Holy Spirit, Peter quoted the Old Testament profusely (Acts 2:14-40). “Those who believed what Peter said were baptized and added to the church that day—about 3,000 in all.” (Acts 2:41)

Here is a list for those interested to read more.
Old Testament texts from the prophets quoted in the New Testament:
Isa 1:9 Rom 9:29
Isa 6:9-10 Matt 13:14-15, Mark 4:12, Acts 28:26-27
Isa 6:9 Luke 8:10
Isa 6:10 Joh 12:40
Isa 7:14 Matt, 1:23
Isa 8:12-13 1 Pet 3:14-15
Isa 8:17-18 Heb 2:13
Isa 9:1-2 Matt 4:15-16
Isa 11:10 Rom 15:12
Isa 13:10 Matt 24:29, Mark 13:24-25
Isa 34:4 Luke 21:26
Isa 22:13 1 Co 15:32
Isa 25:8 1 Co 15:54, Rev 7:17
Isa 26:19 Matt 11:5
Isa 35:5-6 Luke 7:22
Isa 26:20 Heb 10:37-38
Isa 28:11-12 1 Co 14:21
Isa 29:13 Matt 15:8-9, Mark 1:3, Joh 1:23
Isa 40:6-8 1 Pet 1:24-25
Isa 40:13 Rom 11:34, 1 Co 2:16
Isa 42:1-4 Matt 12:18-21
Isa 45:23 Rom 14:11
Isa 49:6 Acts 13:47
Isa 49:8 2 Co 6:2
Isa 52:5 Rom 2:24
Isa 52:7 Rom 10:15
Isa 52:11 2 Co 6:17
Isa 52:15 Rom 15:21
Isa 53:1 Joh 12:38, Rom 8:17
Isa 53:7-8 Acts 8:32-33
Isa 53:9 1 Pet 2:23
Isa 53:12 Luke 22:37
Isa 54:1 Gal 4:27
Isa 54:13 Joh 6:45
Isa 55:3 Acts 13:34
Isa 55:10 2 Co 9:10
Isa 56:7 Matt 21:13
Jer 7:11 Mark 11:17, Luke 19:46
Isa 59:7-8 Rom 3:15-17
Isa 59:20-21 Rom 11:26-27
Isa 61:1-2 Luke 4:18-19
Isa 62:11 Matt 21:5
Isa 64:3 1 Co 2:9
Isa 65:1-2 Rom10:10-21
Isa 65:17 2 Pet 3:13
Isa 66:1-2 Acts 7:49-50
Jer 5:21 Mark 8:18
Jer 9:23 1 Co 1:31, 2 Co 10:17
Jer31:15 Matt 2:18
Jer 31:31-34 Heb 8:8-12
Ezk 11:20 Rev 21:7
Ezk 37:5, 10 Rev 11:11
Dan 3:6 Matt13:42, 50
Dan 7:13 Matt 24:30, 26:64, Mark 13:26,14:62, Luke 21:27,22:69
Dan 9:27 Matt 24:15
Dan 11:31 Mark 13:14
Hos 2:1, 3 Rom 9:25-28
Hos 6:6 Matt 9:13, Matt 12:7
Hos 10:8 Luke 23:30, Rev 6:16
Hos 11:1 Matt 2:15
Hos 13:14 1 Co 15:55
Joel 3:1-5 Acts 2:17-21, Rom 10:13
Amos 5:25-27 Acts 7:42-43
Amos 9:11-12 Acts 15:16-17
Jonah 2:17 Matt 12:40
Mic 5:2 Matt 2:6
Mic 7:6 Matt 10:35-36
Hab2:3-4 Rom 1:17, Gal 3:11
Hab 1:5 Acts 13:41
Hag 2:6, 21 Heb 12:26
Zac 8:16 Eph 4:25
Zech 9:9 Joh 12:15
Zac 11:12-13 Matt 27:9-10
Zac 12:10 Joh 19:37
Zac 13:7 Matt 26:31, Mark 14:27
Mal 1:2-3 Rom 9:13
Mal 3:1 Matt 11:10, Mark 1:2,Luke 7:27
Mal 4:5-6 Matt 17:10-11

Habakkuk 2:3-4 New King James Version (NKJV)
3 For the vision is yet for an appointed time;
But at the end it will speak, and it will not lie.
Though it tarries, wait for it;
Because it will surely come,
It will not tarry.
4 “Behold the proud,
His soul is not upright in him;
But the just shall live by his faith.

Zechariah 2: God measures and refines.

We read Zechariah 2 from NKJV today. Zechariah 2 New King James Version (NKJV) After speaking good and comforting words to the prophet, God immediately sends a warning of the worship standard He requires. He speaks of Himself as a consuming fire. He speaks of dwelling in the midst of His people.
First, God sees and measures. He has a plumb-line. His words are His plumb-line. 
The remnants of the children of Israel (representing the people of God) had started re-building the temple but halted and procrastinated for twenty years (from the time the remnants returned to Jerusalem and the foundation laid to the time the temple was ready for consecration). In the meantime they built their own businesses, houses, accumulated wealth etc. for themselves. (In the book of Haggai, some Israelites even abandoned their first wives and married foreign women, cheated their employees of wages, tried to cheat God by offering sick and defective animals. in short, they simply did not believe in God.) The two prophets: Haggai and Zechariah were sent by God to warn them and urge them to return to God and resume the building work. Not giving God a mere cheap lip service but really obeying God’s words from the hearts and the following the spiritual leading of the Holy Spirit. For God is the God of glory.

Revelation 11:1

[ The Two Witnesses ] Then I was given a reed like a measuring rod. And the angel stood, saying, “Rise and measure the temple of God, the altar, and those who worship there.

A second point is He is a consuming fire (Hebrews 12:29). Why does He mention He will be the wall of fire for His chosen dwelling?
Fire refines believers (the people of God). Zechariah 13:9 I will bring the one–third through the fire, Will refine them as silver is refined, And test them as gold is tested. They will call on My name, And I will answer them. I will say, ‘This is My people’; And each one will say, ‘The Lord is my God.’”
Fire eliminates the idols and unclean spirits. Deuteronomy 4:24 For the Lord your God is a consuming fire, a jealous God.
Fire destroys the evil works of the devil. Deuteronomy 9:3 Therefore understand today that the Lord your God is He who goes over before you as a consuming fire. He will destroy them and bring them down before you; so you shall drive them out and destroy them quickly, as the Lord has said to you.
Third point: The Lord God Almighty says very clearly He has chosen to take possession of His dwelling and He will dwell in the midst of His people.

John 14:10

Do you not believe that I am in the Father, and the Father in Me? The words that I speak to you I do not speak on My own authority; but the Father who dwells in Me does the works.

John 2:21

But He was speaking of the temple of His body.

John 14:17

the Spirit of truth, whom the world cannot receive, because it neither sees Him nor knows Him; but you know Him, for He dwells with you and will be in you.

1 Corinthians 6:19

Or do you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own?

__________________________Zechariah 2

Vision of the Measuring Line

Then I raised my eyes and looked, and behold, a man with a measuring line in his hand. ² So I said, “Where are you going?”

And he said to me, “To measure Jerusalem, to see what is its width and what is its length.”
³ And there was the angel who talked with me, going out; and another angel was coming out to meet him, ⁴ who said to him, “Run, speak to this young man, saying: ‘Jerusalem shall be inhabited as towns without walls, because of the multitude of men and livestock in it. ⁵ For I,’ says the Lord, ‘will be a wall of fire all around her, and I will be the glory in her midst.’”
Future Joy of Zion and Many Nations
⁶ “Up, up! Flee from the land of the north,” says the Lord; “for I have spread you abroad like the four winds of heaven,” says the Lord. ⁷ “Up, Zion! Escape, you who dwell with the daughter of Babylon.”
⁸ For thus says the Lord of hosts: “He sent Me after glory, to the nations which plunder you; for he who touches you touches the apple of His eye. ⁹ For surely I will shake My hand against them, and they shall become spoil for their servants. Then you will know that the Lord of hosts has sent Me.
¹⁰ “Sing and rejoice, O daughter of Zion! For behold, I am coming and I will dwell in your midst,” says the Lord. ¹¹ “Many nations shall be joined to the Lord in that day, and they shall become My people. And I will dwell in your midst. Then you will know that the Lord of hosts has sent Me to you. ¹² And the Lord will take possession of Judah as His inheritance in the Holy Land, and will again choose Jerusalem. ¹³ Be silent, all flesh, before the Lord, for He is aroused from His holy habitation!”