John Howe (1630-1705), English Puritan pastor, preached a series of 13 sermons on regeneration, based on 1 John 5:1, in which he makes statements directly pertinent to an understanding of the foundation of Christian motivation. Notice in paragraph 2 that God's promises are instruments used, but not the foundation itself, to effectual motivation.
"[T]hat holy rectitude which is effected by regeneration, or this new birth, takes place in every thing belonging to the nature of man. Therefore be not so vague as to imagine, that if there be somewhat done in some one faculty, this is regeneration, or that this speaks a man new born. If now and then there be a right thought injected and cast in, if there be an inclination, some motion or desire; if something of convictive light be struck into a man’s conscience; is this regeneration? Is this being new born? No, that makes all things new: ‘If any man is in Christ, he is a new creature; old things are done away, all things are become new.’ There is a new mind, a new judgment, a new conscience, a new will, new desires, new delights, new love, new fear, every thing new."
"Here is a change to be wrought in his nature, a nature that is corrupt, depraved, averse from God, alienated from the divine life; this nature is now to be attempered to God, made suitable to him, made propense and inclined towards him. This might be done, it is true, by an immediate exertion of Almighty power, without any more ado. But God will work upon men suitably to the nature of man. And what course doth he therefore take? He gives 'exceeding great and very precious promises,' and in them he declares his own good will, that he might win theirs. In order to the ingenerating grace in them, he reveals grace to them by these great and precious promises. And what is grace in us? Truly grace in us is good will towards God, or good nature towards God; which can never be without a transformation of our vicious, corrupt nature. It will never incline towards God, or be propense towards God, till he make it so by a transforming power. But how doth he make it so? By discovering his kindness and goodness to them in 'exceeding great and precious promises,' satisfying and persuading their hearts. . . . Thus the 'exceeding great and precious promises' are instruments to the communicating a divine nature to us, though that divine nature be ingenerated by a mighty power."
"It is a creature of a very peculiar benignity and goodness. . . . This goodness shows itself in . . . an habitual propension thereunto, so as to do good with complacency and delight; so this goodness imitates the Divine goodness; he exerciseth loving-kindness in the earth, because he delights therein; so doth the good man do good even with delight, tasting and relishing his own act in what he doth. Oh, how sweet is it to do good! He tastes and the relish of it more than the receiver of it doth, incomparably more; according to that motto of our Lord, ‘It is more blessed to give than to receive.’ A more blessed thing, a thing that carries more sweet and savour in it. . . . Oh, what a pleasant savour hath grace and goodness! Oh, the sweet relishes of it! . . . when regeneration makes a man good, produceth a divine creature, his delight is in doing good as God’s own is."
--Edmund Calamy, ed., The Works of the Rev. John Howe, (London: William Ball, 1838), 895-910. Calamy also wrote a biography of Howe.