Idolatry of the heart

IDOLATRY is the sin of the entire human race. When we speak of idolatry we need not think of blocks of wood and stone, and men bowing down before them; for our native land swarms with idolaters. Neither need you go into the streets to find them: stay where you are, and look into your own hearts, and you shall find idols there. This is the one easily besetting sin of our nature-to turn aside from the living God and to make unto ourselves idols in some fashion or another; for the essence of idolatry is this-to love anything better than God, to trust anything more than God, to wish to have a God other than we have, or to have some signs and wonders by which we may see him, some outward symbol or manifestation that can be seen with the eye or heard with the ear rather than to rest in an invisible God and believe the faithful promise of Him whom eye hath not seen nor ear heard. In some form or other this great sin is the main mischief in the heart of man; and even in saved men this is one of the developments of remaining corruption. We may very easily make an idol of anything, and in different ways. No doubt many mothers and fathers make idols of their children, and so many husbands and wives idolize each other. Equally is it certain that many a thoughtful man makes an idol of his intellect, and many another makes an idol of his gold, or even of that little home wherein he enjoys so much contentment. Anything, however holy, which comes between us and the personal dealing of our soul with God, as he is revealed in Christ Jesus, by faith and love and hope, becomes an idol to us. – C.H. Spurgeon

"...we may gather that man's nature…is a perpetual factory of idols" (Institutes I.xi.8).
-John Calvin