John 4:24
24 God is a Spirit: and they that worship him must worship him in spirit and in truth.
John 16:12-14
The Spirit of Truth
12 “I have much more to say to you, more than you can now bear. 13 But when he, the Spirit of truth, comes, he will guide you into all truth. He will not speak on his own; he will speak only what he hears, and he will tell you what is yet to come. 14 He will bring glory to me by taking from what is mine and making it known to you. 15 All that belongs to the Father is mine. That is why I said the Spirit will take from what is mine and make it known to you.
For me it is hard to understand about God being a Spirit, and the Spirit of Truth...But we can tell the Holy Spirit, which is the Spirit of Truth and our Father, who is a Spirit are related...I look at it this way, it is the Divine Energy of All Life and in all Life that controls life itself...That is my humble description of God, our LORD and Savior...He is hope and life itself...I know He is a Living God, a Spiritual Being and He is Supreme...