'Faithlessly' in the Bible

I will make the land desolate (ruined, deserted), because they have acted unfaithfully [through their idolatry],’ says the Lord God.”

“Therefore, son of man, speak to the house of Israel and say to them, ‘Thus says the Lord God, “Again in this your fathers have blasphemed Me, in that they acted faithlessly and treacherously against Me.