Bible Verses About Sincerity: Our service to God

Now therefore fear the LORD, and serve him in sincerity and in truth: and put away the gods which your fathers served on the other side of the flood, and in Egypt; and serve ye the LORD.

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.

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