You’ve seen the locks on bridges. You can see it anywhere: in Portland, Paris, or any number of hikes in the Pacific NW. The symbolism isn’t lost on us. People in love put those locks there. They take the keys with them or throw them away, so that the lock has (relative) permanence.
They’re portraying a promise of faithfulness; that their love for one another is sturdy, stable, and lasting. But we know the truth about ourselves…we can be fickle. We don’t always follow through an enact our best intentions – whether to a particular commitment or a person. God’s love, and his redeeming intentions toward us never change or fail. Christ is perfectly faithful. In Rev 19, he’s even named as “Faithful and True.” In faithfulness, he fulfills every promise, and he accomplishes everything he sets out to do. That includes his promise to make his own people faithful through the fruit-bearing work of his Spirit.
“Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.” Hebrews 2
We have no faithfulness of our own, but by the Spirit’s work, he is making us more like himself in this as well. So then “let us hold fast the confession of our hope without wavering, for he who promised is faithful.” Hebrews 10
“His master said to him, ‘Well done, good and faithful servant. You have been faithful over a little; I will set you over much. Enter into the joy of your master.’” Matt 25