Religion, as ordered by God, is not weak or lifeless, but rather ardent in spirit and vigorously practiced. This is confirmed in Romans 12:11, Deuteronomy 10:12, and 6:4–5. It is the fruit of true regeneration, or heart circumcision, and holds the promise of life. God expects us to fear and love Him, to walk in His footsteps, and to serve Him with all our hearts and souls. This intense, vigorous spiritual engagement is the result of true heart circumcision, or regeneration, and it holds the promise of life.
That religion which God requires, and will accept, does not consist in weak, dull and lifeless wouldings, raising us but a little above a state of indifference: God, in his Word, greatly insists upon it, that we be in good earnest, fervent in spirit, and our hearts vigorously engaged in religion: Romans 12:11, “Be ye fervent in spirit, serving the Lord.” Deuteronomy 10:12, “And now Israel, what doth the Lord thy God require of thee, but to fear the Lord thy God, to walk in all his ways, and to love him, and to serve the Lord thy God, with all thy heart, and with all thy soul?” And ch. 6:4–5, “Hear, O Israel; the Lord our God is one Lord; and thou shalt love the Lord thy God, with all thy heart, and with all thy soul, and with all thy might.” ‘Tis such a fervent, vigorous engagedness of the heart in religion, that is the fruit of a real circumcision of the heart, or true regeneration, and that has the promises of life; Deuteronomy 30:6, “And the Lord thy God will circumcise thine heart, and the heart of thy seed, to love the Lord thy God, with all thy heart, and with all thy soul, that thou mayest live.” – Jonathan Edwards, Religious Affections, WJE 2:99