John 4:24

God is Spirit and those who worship Him must worship in spirit and truth."

2 Corinthians 3:17

Now the Lord [i.e., Christ] is the Holy Spirit, and there is freedom [from the bondage of sin and fear] wherever the Spirit of the Lord is.

Matthew 15:8-9

These people [claim to] honor me with their lips [i.e., by what they say], but their heart is far from [honoring] me.

Philippians 3:3

For we [Christians] are the [true] circumcision [i.e., the real "Jews" in God's eyes. See Rom. 2:28-29]. We worship by means of God's Holy Spirit [i.e., are empowered and motivated by the Holy Spirit], and boast in [the person and work of] Christ Jesus, and [we] place no confidence in the flesh [i.e., in any outward ritual or status for salvation].

2 Corinthians 1:12

For this is what we boast of: Our conscience testifies that we have conducted ourselves in the world, and especially toward you, in holiness and godly sincerity, not with human wisdom, but with the favor of God.

1 Timothy 1:17

Now, may there be honor and praise forever and ever to the eternal King, the immortal, invisible, only God. May it be so.

Treasury of Scripture Knowledge

Summary

God is a Spirit: and they that worship him must worship him in spirit and in truth.

Bible References

A spirit

2 Corinthians 3:17
Now the Lord [i.e., Christ] is the Holy Spirit, and there is freedom [from the bondage of sin and fear] wherever the Spirit of the Lord is.
1 Timothy 1:17
Now, may there be honor and praise forever and ever to the eternal King, the immortal, invisible, only God. May it be so.

Must

Matthew 15:8
These people [claim to] honor me with their lips [i.e., by what they say], but their heart is far from [honoring] me.
2 Corinthians 1:12
For this is what we boast of: Our conscience testifies that we have conducted ourselves in the world, and especially toward you, in holiness and godly sincerity, not with human wisdom, but with the favor of God.