There is no article before “spirit” in the Greek.  Jesus is saying that the essential nature of God is spirit.  (cf. “God is light” and “God is love.” 1John 1:5, 4:8)  God is not of a material nature and thus not bound to any place or thing.

1 John 1:5  This is the message we have heard from him and declare to you: God is light; in him there is no darkness at all.

1 John 4:8  Whoever does not love does not know God, because God is love.

“must” means “Here is the real necessity (dei), not the one used by the woman about the right place of worship (verse #20).” (RWP)

Since God is essentially spirit, real worship of Him must necessarily be of a spiritual nature.  “To worship God in spirit is not a possibility that is always and everywhere open to man…” (G.S. Hendry qt’d in Morris p. 272)  “Man cannot dictate the ‘how’ and ’when’ of worship.  He must come only in the way that the Spirit of God opens to him.” (Morris p. 272) We can always thank God or praise Him because those actions come out of our minds, which are part of our souls, but we cannot always worship Him, for true worship comes from our spirits, which are not yet complete in their relationship with our wills (or His!) What we can do is to put ourselves in a position to worship and then trust the Holy Spirit to lead our spirits into God’s Presence. Example: have you ever been in a worship service where other people are obviously experiencing the Presence of God, but you aren’t? They have entered into worship, but you are still stuck in praise. The reason for this is that you can only worship with your spirit, not your mouth or your brain.

The Greek word for worship in the New Testament is proskuneo, which means “to kiss toward.”  The words for worship in the Old Testament have to do with physically prostrating oneself and offering obeisance (a gesture of respect or reverence) to the One being worshipped.  From this we may obtain the following definition:

Worship is a feeling of admiring awe, astonished wonder, and great love in one’s heart for God accompanied with an outward expression of those feelings.

The purpose of man is to worship God.  The shorter catechism states: “The chief end of man is to glorify God and enjoy Him forever.”  The purpose for our existence is to bring pleasure and glory to God.

Col 1:16-17 For by him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things were created by him and for him. He is before all things, and in him all things hold together.

Isaiah 43:7 everyone who is called by my name, whom I created for my glory, whom I formed and made.”

Isaiah 43:21 the people I formed for myself that they may proclaim my praise.

The goal of God is relationship.  He had a relationship with Adam before the fall as He walked with him in the garden and spoke with him.  Notice also His relationship with Enoch and Abraham:

Genesis 5:24 Enoch walked with God; then he was no more, because God took him away.

James 2:23 And the scripture was fulfilled that says, “Abraham believed God, and it was credited to him as righteousness,” and he was called God’s friend.

Jesus was sent to bring us back into relationship with God. 

John 14:21 Whoever has my commands and obeys them, he is the one who loves me. He who loves me will be loved by my Father, and I too will love him and show myself to him.”

We were created with a need to worship God.  When we can’t or won’t express that need, it comes out in other areas such as drugs, sex, work, television, etc.  An example is:

Eph 5:18 Do not get drunk on wine, which leads to debauchery. Instead, be filled with the Spirit.

The Samaritan woman at the well was expressing this need through her many husbands.  Jesus recognized the longing within her and ministered to her need.

Jesus is not recorded as teaching his disciples about worship.  Why didn’t He teach them here instead of a Samaritan woman?  (Because they wanted food!)  God seems to choose people based on their hunger for Him.  God is interested in what is inside a person.  The “why” in worship is very important to God.

The woman was confused as to the place of worship.  Worship is an expressed attitude, not a religious act.  The Who and the why are of utmost importance; the where, when, and how are subservient to them.  We get lost in the style, form, and traditions of worship to the point that we lose the reality of getting to know Him and show Him how much we love and exalt Him.

Jesus told the woman that true worshippers worship the Father in spirit and in truth but there is a warning that comes with this.  Worship in spirit and in truth is not cozy, safe, and comfortable; it is confusing!  Religion is not confusing but true worship is, for God is the revealer of our confusion. When He shows us a little bit of Himself, we find that He isn’t at all like we thought.  God’s thoughts and ways are infinitely higher than ours.  (Remember His attribute of transcendence?) 

Isaiah 55:8-9 “For my thoughts are not your thoughts, neither are your ways my ways,” declares the LORD. “As the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts.

God’s ways and thoughts are so much higher than ours that our natural minds become confused.  Our answer to this problem is that we often lower God’s revelation of Himself to something we can handle in our experience level.  The disciples did this when they thought Jesus was going to establish an earthly kingdom, even though He had told them many times that He was going to suffer and die and that His kingdom was not of this earth.  When we lower the revelation of God to something less, we lower the quality of our worship, often to the point where it is not worship at all.

For us to worship God in spirit and in truth, we must see Him for Who He is, not for what He does.  John never worshipped Jesus until he saw Him exalted in heaven.  It is the same with us.  We see Him as Savior, Sanctifier, Healer, Provider, but we can only worship Him when we see him as King of kings and Lord of lords. We will thank Him and praise Him for those other things, but worship is an expression of love, not of thanks. One example would be of a husband coming home after being away on a business trip.  Can you imagine how he would feel if his wife said, “I’m so glad you are home, because the faucet is leaking, the door needs fixed, and I’m out of cash?”  The man is looking for a love response of hugs and kisses and so is God. 

The purpose of our worship can never be to get something out of God.  Think of how that must make Him feel!  We also must never worship because we are ordered to or because it is expected of us.  That is not worship at all, but work.  Again, think of how it must make God feel to have so-called “worship” expressed to Him with this motivation.  The reasons we worship God are all-important to Him.

True worship comes out of us when we stand in awe of Him and want to tell Him how much we love Him.  The reason for us to worship God is very simple: because He is worthy!

Revelation 4:11 “You are worthy, our Lord and God, to receive glory and honor and power, for you created all things, and by your will they were created and have their being.”

God is worthy of our worship so let us do so in spirit and in truth as He tells us to do!