Bible Verses About Sincerity: Our service to God

Now therefore fear Jehovah, and serve him in sincerity and in truth; and put away the gods which your fathers served beyond the River, and in Egypt; and serve ye Jehovah.

But the hour cometh, and now is, when the true worshippers shall worship the Father in spirit and truth: for such doth the Father seek to be his worshippers.

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