A well-known symbol of Lutheranism is the so-called Luther Rose, which features a black cross on a red heart at the center. It was devised for Luther in 1530 and features multivalent symbolism. Luther claimed that:
my seal is a symbol of my theology. The first should be a black cross in a heart, so that I myself would be reminded that faith in the Crucified saves us. Although it is indeed a black cross, which mortifies and which should also cause pain, it leaves the heart in its natural color. Such a heart should stand in the middle of a white rose, to show that faith gives joy, comfort, and peace. Such a rose should stand in a sky-blue field, symbolizing that such joy in spirit and faith is a beginning of the heavenly future joy, which begins already, but is grasped in hope, not yet revealed. And around this field is a golden ring, symbolizing that such blessedness in Heaven lasts forever and has no end.
“I wonder what symbol Calvin used?” I mused to my wife at dinner last night. “Probably a tulip,” she replied with eminent good sense. TULIP, of course, is an acronym for the five points of Calvinist theology, viz:
Perseverance of the saints
Instead, as it turns out, Calvin did not use a flower, but a heart, held in a hand, illustrating the motto “Cor meum tibi offero, Domine, prompte et sincere,” that is, “My heart I offer to you, O Lord, promptly and sincerely.”
I’m not sure who drew this but I found it at The Josh Link.
This seventeenth-century medal was struck in memory of Calvin, and the image can be found at the Calvin University (Grand Rapids) website.
Calvin University itself uses a version of the emblem and motto.
The more you know! Personal emblems, especially if properly heraldic, ought to make a comeback.