To be unfaithful is to lack dedication or devotion to a cause, ideal, or person.
The Bible warns us against being unfaithful to God.
See faithful.
Key verse about unfaithful: “When anyone is unfaithful to the Lord by sinning unintentionally in regard to any of the Lord’s holy things, they are to bring to the Lord as a penalty a ram from the flock, one without defect and of the proper value in silver, according to the sanctuary shekel. It is a guilt offering. (Leviticus 5:15, NIV).
A lifelong student of the Bible, Peter DeHaan, PhD, wrote the 1,000-page website ABibleADay.com to encourage people to explore the Bible. His main blog and many books urge Christians to push past the status quo and reconsider how they practice their faith in every area of their lives.