Truth is veiled for witnesses. They are convinced they are worshiping in truth. When in fact, the truth the bible is referring to is here in Corinthians. Verse 3 refers to the those who are veiling truth and still calling it good news, notice that they perish.
In the later verses we are told that the real good news or truth is that, Jesus is Lord, Love him. Witnesses go contrary to verse 5 where it says not to preach about yourselves but to preach about Jesus. They do not preach about Jesus.
(2 Corinthians 4:1-6) 4 That is why, since we have this ministry according to the mercy that was shown us, we do not give up; 2 but we have renounced the underhanded things of which to be ashamed, not walking with cunning, neither adulterating the word of God, but by making the truth manifest recommending ourselves to every human conscience in the sight of God. 3 If, now, the good news we declare is in fact veiled, it is veiled among those who are perishing, 4 among whom the god of this system of things has blinded the minds of the unbelievers, that the illumination of the glorious good news about the Christ, who is the image of God, might not shine through. 5 For we are preaching, not ourselves, but Christ Jesus as Lord, and ourselves as YOUR slaves for Jesus' sake. 6 For God is he who said: "Let the light shine out of darkness," and he has shone on our hearts to illuminate [them] with the glorious knowledge of God by the face of Christ.
Also he quoted you Math 7: 21. That was ironically talking about False Prophets. Plus it's talking about how to get into heaven.
(Matthew 7:21) 21 "Not everyone saying to me, ‘Lord, Lord,' will enter into the kingdom of the heavens, but the one doing the will of my Father who is in the heavens will.
So what is the fathers will.
Preaching about his son.
So if gods word is truth then he would get into heaven for doing gods will. What? Heaven!
The scripture about the Boreans is dumb to quote too. It encourages studying the scriptures. Not watchtowers
Sorry I rambled, It's just such stupid reasoning.
So now I dodged your question. LOL
Ask him to tell you exactly what the good news is. Using only scriptures. He will be forced to actually look for it and will be surprised to find it's not what they are preaching.
tt