Some say that to worship “in spirit” means to pray and sing in other tongues, but that seems to be a strained interpretation in light of Jesus’ words. He said that “an hour is coming, and now is, when the true worshipers shall worship the Father in spirit and truth,” indicating that there were already those who met the conditions for worship “in spirit” when He made His statement. Of course, no one spoke in tongues until the day of Pentecost. Therefore, any believer, whether he can speak in tongues or not, can worship God in spirit and in truth. Praying and singing in other tongues can certainly aid a believer in his worship, but even praying in tongues can become a heartless ritual.
An interesting insight into the worship of the early church is found in Acts 13:1-2:
Now there were at Antioch, in the church that was there, prophets and teachers; Barnabas, and Simeon who was called Niger, and Lucius of Cyrene, and Manaen who had been brought up with Herod the tetrarch, and Saul. And while they were ministering to the Lord and fasting, the Holy Spirit said, “Set apart for Me Barnabas and Saul for the work to which I have called them” (emphasis added).
Notice this passage said they were “ministering to the Lord.” It seems reasonable to think that means they were worshiping Him, and thus we learn that true worship actually ministers to the Lord. That is only true, however, when the Lord is the object of our love and affection.