'Sincerity' in the Bible

Therefore let us keep our festival not with old yeast nor with the yeast of what is evil and mischievous, but with bread free from yeast--the bread of transparent sincerity and of truth.

We are not again commending ourselves to your favour, but are furnishing you with a ground of boasting on our behalf, so that you may have a reply ready for those with whom superficial appearances are everything and sincerity of heart counts for nothing.

And our prayer to God is that you may do nothing wrong; not in order that our sincerity may be demonstrated, but that you may do what is right, even though our sincerity may seem to be doubtful.

May grace be with all who love our Lord Jesus Christ with perfect sincerity.

let us draw near with sincerity and unfaltering faith, having had our hearts sprinkled, once for all, from consciences oppressed with sin, and our bodies bathed in pure water.