diligence - characterized by steady, earnest, and energetic effort; painstaking, showing you care
fervent - greek word: zeo; #2204; learning fervor, fiery hot; full of burning zeal, opposite of cold, dignified, unemotional.
In a Christian context, fervent signifies a high spiritual temperature, inflamed by the Holy Spirit
Christian behavior is about being diligent, fervent
(on fire for the Lord and His word) and serving the Him.