Answer: Jesus made his comment about the need to worship our Father in spirit and truth when he talking to a Samaritan woman at the well of Jacob. In John 4:23 he tells the woman that God is seeking those who are willing to worship him "in spirit and in truth."
The Scriptures say that the Word of God is true (John 1:14) and that Jesus is Truth (Psalms 119:160; John 14:6) incarnate. It also states that the Bible is a lamp to guide the ways of a person (Psalms 119:105). Now that we know a little about what is true, how do we combine it with the spirit in our worship?
We read in the Old Testament the specific details about what was required of the Priests and Levites before they could minister before the Lord God. The Bible also tells us, however, that something changed when Jesus died on that stake 2,000 years ago. The veil in the Temple was torn from top to bottom when our Savior died, which meant that believers now had direct access to God.
In order to worship God properly we need to look at the spiritual meaning of some of the last six commandments. The fifth commandment states we are supposed to honor our mother and father. By doing this in the physical letter, we are also honoring God the Father as the ultimate parent of all mankind.
The sixth commandment declares we are not to murder another human being. The intent of this commandment is that we should not even hate another human or hold a grudge. The seventh commandment states "in the letter of the law" that we are not to commit adultery. Its intent, however, means we are not to lust in our hearts for another person and to be faithful to our marriage partner.
The ninth commandment declares we are not to bear false witness, which means we are not to even exaggerate a story. The tenth, and last, commandment says we are not to covet what does not belong to us, which spiritually means we should be content with what we have already and be thankful for it.
The commandments are not followed, sadly, by the world. This means that when we seek to worship God IN SPIRIT and IN TRUTH we are going against everything around us. We must seek after Him to lead us and give us the ability to be fully obedient to him.
Our ultimate goal in life should be to "take captive" all of our thoughts until they are the same ones that Jesus would have (2Corinthians 10:3 - 6). The process of conversion is made possible through the death of Jesus. As we become more and more like our Savior, our worship becomes more meaningful and we have a closer relationship with our heavenly Father.
God is love. He would never create any law that is not for the ultimate good of mankind. We need to give God the Father and Jesus Christ the highest praise and honor in our worship with our whole heart and being. We need to obey everything that comes from his mouth whether written or spoken. We need to be in a state of continual repentance for our erroneous thoughts and behavior once we understand that it is contrary to what is written in Scripture.
We are to give of ourselves joyously to help others come to the same understanding. We are to fellowship with those who are also being led by God. We are additionally to conduct our lives such that it seeks to please (Romans 12:1). All this will greatly aid us to worship God both in spirit and in the truth.