To Worship in Spirit and Truth

John 4:23
(23)  But the hour cometh, and now is, when the true worshippers shall worship the Father in spirit and in truth: for the Father seeketh such to worship him.

I've recently been reading in the Old Testament, and have been much impressed that behind all the ceremonial symbolism of the sacrificial system, there is a principle of worship that transcends into the New Covenant. That principle is to rejoice and be thankful.

The Law's Command to Rejoice and Give Thanks

Deuteronomy 26 gives instructions for the covenant people to bring their first fruits and their tithes before God. There were specific prayers and confessions that were commanded to be made when these offerings were brought before God. For example, when giving their first fruits to the LORD, they were to say a prayer that confessed how God had redeemed them from Egyptian bondage and brought them into the land of promise. They were to confess that they had thus brought the first fruits of the land before the LORD, as evidence of His faithfulness to His promise to the fathers. They were then to set the basket down and worship before the LORD.

Deuteronomy 26:10-11
(10)  And now, behold, I have brought the firstfruits of the land, which thou, O LORD, hast given me. And thou shalt set it before the LORD thy God, and worship before the LORD thy God:
(11)  And thou shalt rejoice in every good thing which the LORD thy God hath given unto thee, and unto thine house, thou, and the Levite, and the stranger that is among you.

The command to be thankful and rejoice was not to be taken lightly. Deuteronomy 28 contains the long list of curses that would fall on the covenant people if they were unfaithful to the commands of God. But curiously, toward the end of the curses, God gives the primary reason for his displeasure as a lack of joy and thankfulness among His people.

Deuteronomy 28:46-47
(46)  And they [the curses] shall be upon thee for a sign and for a wonder, and upon thy seed for ever.
(47)  Because thou servedst not the LORD thy God with joyfulness, and with gladness of heart, for the abundance of all things;

When we read this, could we conclude that a lack of thankfulness is the root behind much, if not all of the unfaithfulness that God's covenant children exhibit?

Thanksgiving in the Tabernacle of David

David is a name that is rightly associated with worship. Although a warrior and king, worship was his passion as evidenced by his organization of the 5 books of the Psalter, and especially by his organization of the worship surrounding the Ark of the Covenant. In the act of bringing the Ark of the Covenant home from the land of the Philistines, David orchestrated the processional march to be a joyful worship celebration.

1 Chronicles 15:25
(25)  So David, and the elders of Israel, and the captains over thousands, went to bring up the ark of the covenant of the LORD out of the house of Obededom with joy.

The joyful celebration would not end when David brought the Ark back home to the covenant people. The king who was also the nation's worship leader had a special tent pitched for the Ark close to his own home. At this site, David appointed permanent shifts of singers and musicians to continue the celebration and thanksgiving every day, and every hour of the day.

1 Chronicles 16:4-6
(4)  And he appointed certain of the Levites to minister before the ark of the LORD, and to record, and to thank and praise the LORD God of Israel:
(5)  Asaph the chief, and next to him Zechariah, Jeiel, and Shemiramoth, and Jehiel, and Mattithiah, and Eliab, and Benaiah, and Obededom: and Jeiel with psalteries and with harps; but Asaph made a sound with cymbals;
(6)  Benaiah also and Jahaziel the priests with trumpets continually before the ark of the covenant of God.

Jesus and the Lifestyle of Joy and Thanksgiving

It is easy enough to see the emphasis on thanksgiving and rejoicing that Jesus made. A quick search of the concordance will reveal the word "rejoice" and "thanksgiving" used repeatedly in the context of Jesus' ministry. But I think the most telling passage is how the resurrected Christ was revealed to the two disciples on the road to Emmaus. These two disciples did not recognize who Christ was until they sat down to eat together and Christ blessed the food (Lu. 24:30-31). Blessed is translated from the Greek word eulogeo, which means to give solemn thanks. Luke 24:35 specifically relates that the disciples finally recognized the Lord in the breaking of bread--i.e. they recognized the way Christ gave thanks for their meal. This could only be true because Jesus was a man who regularly gave heartfelt praise and thanksgiving to the Father.

What Does it Mean to Worship in Spirit and in Truth?

I have a pentecostal background, and as most folks know, the worship services in the churches of my youth were lively. We were blessedly free from the stodginess that has been known to grip many older denominations. We also were sometimes guilty of ridiculous excesses (I have witnessed legs being broken in some pentecostal services that got so out of control as to become more like a circus than a religious gathering.)
We were always quick to point out (only sometimes with a prideful heart) that Christ said that true worshipers would worship in spirit and in truth. I fully believed then that worship in spirit and truth looked like a pentecostal church service--loud and unashamedly emotional.
I still prefer worship that is expressive and unbound. I appreciate the beauty and tradition of some liturgical worship traditions, but I am only at home when I am free to raise my hands and shout, or bow my head and cry.
But I no longer maintain that we are worshiping in spirit and truth just because we clap our hands or shout in the church house. We do not fulfill the Lord's word regarding worship just because we pray in tongues, or practice any other of the many legitimate pentecostal/charismatic expressions of worship. (Neither do I maintain that we are worshiping in truth, because we presume to have correct doctrine--this is a source of terrible religious pride that I have first hand experience with).
The Lord has led me to understand that true worshipers lead a lifestyle of joy and thanksgiving. This is the doctrinal truth about covenant worship that is presented in the Old Testament. We worship in doctrinal truth when we confess the goodness of God in our daily lives, and not just in our corporate meetings.We worship in spirit when our confession comes from a heart of honesty and integrity, and not just from our trained lips.
Just as the Old Testament Israelites could go through the motions of bringing their offerings to God, yet their hearts could be far from Him, so can we go through the motions of worship without our hearts being truly thankful. You can jump and shout and run the isles (if your church permits it!), and still not worship God in spirit and truth if you are not living a lifestyle of joy and thanksgiving.
I have made the commitment to honor God with a joyful heart and thanksgiving at all times, notwithstanding my circumstances. I am reminded of the warning by the Apostle that men would be unthankful in the last days (2 Tim 3:2). I choose to follow the command to rejoice and give thanks in every circumstance according to the will of God.

1 Thessalonians 5:16-18
(16)  Rejoice evermore.
(17)  Pray without ceasing.
(18)  In every thing give thanks: for this is the will of God in Christ Jesus concerning you.