"Jesus said to him, ‘I am the way, the truth, and the life. No one comes to the Father except through Me'" (John 14:6). As John wrote the gospel that bears his name, in describing Jesus he said, "…we beheld His glory…full of grace and truth" (John 1:14). He said that grace and truth came through Jesus Christ, and Jesus Himself said that He was truth. Thus we have a beginning definition of truth. It is defined in the person of Christ. We may be quite familiar with Jesus' statement, but what does it mean to us? I believe God wants to give us an increased understanding in all things as we grow in God. If we are to walk in truth, we must know in some measure what this scripture means.
In the scripture from John 16 quoted above, Jesus said that the Holy Spirit would guide us into all truth, and that He would take the things of Jesus and "declare them to us" (make them real to us). If the work of the Holy Spirit is to make the things of Jesus real to us and in us, and if Jesus Himself is the ultimate definition of truth, can we say that truth is everything that pertains to that work? In other words, truth always relates to the person of Christ and the expression of Christ through human vessels. When John saw Christ, he saw truth, or "the word made flesh." It was not an abstract idea that he saw, but the very character and nature of God revealed through a man.
Following this a little further, I believe we can say that truth is everything that brings us into and keeps us in a right relationship with God through Christ. Other things outside of this may be "true" but not the "truth" that we are concerned about. For example, the law of gravity may be "true" and part of God's creation, but it does not directly relate to our relationship with Christ. What God is concerned about is the expression of His life in and through those who were created in the image of God.
Continuing to expand this, we can say that truth encompasses these areas:
All of these together constitute areas of truth that we are called to understand and walk in. In other words, our love for Jesus will result in our obedience to His commands pertaining to truth. "If you love Me, keep My commandments" (John 14:15). We cannot separate Jesus from these areas of truth. To love Jesus is to allow the Holy Spirit to lead us in all of these things. He is "the Spirit of truth" and God has chosen to give Him to indwell us and lead us into all truth. To allow Him to do so results in us being established on a solid foundation in God. To reject God's plan or any part of that plan is to reject God and create our own way. If we seek to find our own way, we will find ourselves outside of God and His grace, for grace and truth are realized in Christ.