“God is a Spirit: and they that worship him must worship him in spirit and in truth.” (John 4:24)
If you are familiar with John 4 you will know that today’s verse is part of the conversation that Jesus had with the woman at the well. Here is the verse in its context, Jesus had just finished talking to the woman about the many husbands that she has had and the conversation continued:
[John 4:19-26] The woman saith unto him, Sir, I perceive that thou art a prophet.  Our fathers worshipped in this mountain; and ye say, that in Jerusalem is the place where men ought to worship.  Jesus saith unto her, Woman, believe me, the hour cometh, when ye shall neither in this mountain, nor yet at Jerusalem, worship the Father.  Ye worship ye know not what: we know what we worship: for salvation is of the Jews.  But the hour cometh, and now is, when the true worshipers shall worship the Father in spirit and in truth: for the Father seeketh such to worship him.  God is a Spirit: and they that worship him must worship him in spirit and in truth.  The woman saith unto him, I know that Messias cometh, which is called Christ: when he is come, he will tell us all things.  Jesus saith unto her, I that speak unto thee am he.
This is a great passage to remind us that we worship the One who is not only our Father, but also the Spirit that gives us the power to walk in a way that pleases the Father (Gal 5:22-25). Jesus was pointing out that the way the people were worshiping while He walked the earth was going to change. He was pointing to the future; the time after the cross. He was telling her that when things change that the Father would know the true worshipers because they would know that worship is an honest and regular part of their life. That the worship was not about the place in which they worship (the mountain or Jerusalem), but it was about “how” they worshiped and “who” they worshiped and “why” they worshiped.
True worship is knowing that we worship the Heavenly Father, the Creator, the One who sacrificed His only begotten Son to save us from certain death (Rom 6:23). True worship is knowing that Our Father deserves uninterrupted time from us that is devoted to Him. True worship is that which we do because we love the Lord. We worship in spirit and in truth when we give our all to the Master because He first loved us (1 John 4:19).