The Bible is a book that bears witness to truth, so every church today seeks truth. Joshua came to this earth to preach the truth and save people. So what was the truth that Joshua preached? Joshua said that the word of God is the truth. But not everyone received the word of God; only the disciples received the word of God.

[John 15:15] no longer call you servants, because a servant does not know his master's business. Instead, I have called you friends, for everything that I learned from my Father I have made known to you.

Yehoshua called his disciples friends because he understood the will of the Father. Therefore, only Joshua and his disciples know the truth (the Word of the Father). Yehoshua told everything in parables to hide his truth. But after the Last Supper, he no longer spoke in parables.

[John 15:25~29] Though I have been speaking figuratively, a time is coming when I will no longer use this kind of language but will tell you plainly about my Father. In that day you will ask in my name. I am not saying that I will ask the Father on your behalf.....(29)Then Jesus' disciples said, "Now you are speaking clearly and without figures of speech.

Yehoshua asked through prayer to sanctify His disciples with the truth.

[John 17:17] Sanctify them through thy truth: thy word is truth.

As Yehoshua said, the Word of the Father is truth. Therefore, we receive a divine transformation by the word of the Father. Therefore, the disciples who realized the Father's words became holy (clean) with the truth.

[John 15:2] You are already clean because of the word I have spoken to you.

The disciples were clean (holy) because they realized the Father's words that Joshua had made known to them. So what did Joshua tell the disciples? What Joshua made known to the disciples was the coming of the Spirit of truth.

[John 14:17] the Spirit of truth. The world cannot accept him, because it neither sees him nor knows him. But you know him, for he lives with you and will be in you 

Yehoshua informed his disciples that the Spirit of truth would come. She said that the Spirit of truth would come and enter the body of the disciples and dwell with them. Then another Judas understood Joshua's words correctly and asked a question.

[John 14:22~23] The other Judas, not Judas Iscariot, then spoke up and asked, "Lord, what do you mean by saying that you will show us what you are like, but you will not show the people of this world?" Jesus replied: If anyone loves me, they will obey me. Then my Father will love them, and we will come to them and live in them.

Joshua said that the spirit of truth would come into the body of the disciples, but before he said this, Joshua said I will come into your body and live in you; my being in you means that Joshua comes as the spirit of truth; therefore, the disciples were sanctified by the word of Joshua, who said that the spirit of truth had come. The truth that Joshua is trying to convey is that the spirit of Joshua comes upon the disciples; Paul testified that the spirit of Joshua would come upon the body of the saints, saying that this was a secret hidden before the foundation of the world.

[Colossians 1:26~27] that is, the mystery which has been hidden from the past ages and generations, but has now been manifested to His saints, to whom God willed to make known what is the riches of the glory of this mystery among the Gentiles, which is Christ in you, the hope of glory

Therefore, the truth that Yehoshua is trying to convey is that the Spirit of Yehoshua will come upon the saints and salvation will be accomplished. Salvation is complete only when the Holy Spirit comes upon us.

[Ezekiel 37:14] My Spirit will give you breath, and you will live again. I will bring you home, and you will know that I have kept my promise. I, the LORD, have spoken."

Joshua came to earth to preach the truth and to bring salvation. The truth that Joshua preached was that the Spirit of Joshua comes upon the saints. Therefore, to be saved, the Spirit of Joshua must come upon us, and this is the truth that Joshua preached. When Pilate asked Joshua what the truth was, Joshua did not answer, because Pilate did not love Joshua. Those who love Joshua will realize that the Spirit of Joshua dwells in the body of the saints. When the Spirit comes upon us, we are saved. 

[Isaiah 59:20~21] "The Redeemer will come to Zion, to those in Jacob who repent of their sins," declares the LORD. "As for me, this is my covenant with them," says the LORD. "My Spirit, who is on you, and my words that I have put in your mouth will not depart from your mouth, or from the mouths of your children, or from the mouths of their descendants from this time on and forever," says the LORD.

Therefore, those who do not understand the truth are under the control of Satan. The truth that God is trying to accomplish is that the Holy Spirit of Yehoshua will come upon the saints to complete salvation.