John 16: 5, 7 and John 15: 26
But now I am going to Him who sent Me. But I tell you the truth, it is to your advantage that I go away; for if I do not go away, the Helper shall not come to you; but if I go, I will send Him to you. When the Helper comes, whom I will send to you from the Father, that is the Spirit of truth, who proceeds from the Father, He will bear witness of Me.
When Jesus went home to be with our Father, he sent a helper to us. This helper is the Holy Spirit of promise. In Acts 1: 4 Jesus commanded his disciples to remain in Jerusalem until they received what the Father had promised telling them that they would receive power when they received the baptism in the Holy Spirit. We are now living in the promised Age of the Holy Spirit.
The 1st Testament was about Father God. We see God, himself, interacting with his people. The Old Testament looked forward to the coming of Jesus with much prophecy. The second Testament or the New Testament is about the life and ministry of Jesus. Everything changed in the earth as a result of Jesus’ ministry. Everyone who wrote in the New Testament times wrote in respect to the new covenant which was bought by and ushered in by Jesus the Christ.
Jesus looked forward to another time too, just like the Old Testament prophets did. He prophesied about the coming of the Holy Spirit, the third person of the Holy Trinity. We are now living in the days of the Third Testament. This is the time of the Holy Spirit. We are to learn about him just like the New Testament people learned about Jesus. As we develop in our relationship and understanding of working with the Holy Spirit, we look forward to another time too. We await the second coming of Christ. Each of the three persons of the trinity will have their own age and we are to get to know each of them in their individuality as well as the collective God head. Then Christ will return in all His glory and we will all be caught up with him and live eternity with God, The Father; Jesus, the son; and the Holy Spirit.