By Richard Sibbes
Let us assure ourselves that God’s grace, even in this imperfect state, is stronger than man’s free will in the state of original perfection.[Adam] It is founded now in Christ, who, as he is the author, so he will finish, [or complete] our faith (Heb.12:2). We are under a more gracious covenant.
What some say of rooted faith,” fides radicata, that it continues, while weak faith may come to nothing” seems to be contradicted by this Scripture; for, as the strongest faith may be shaken, so the weakest, where truth is, is so far rooted that it will prevail.
Weakness with watchfulness will stand, when strength with too much confidence fails. Weakness with acknowledgement of it, is the best place and thing for God to perfect his strength in; for consciousness of our weaknesses drive us out of ourselves to him in whom our strength lies.
From this it follows that weakness may be consistent with assurance of salvation. The disciples, even with all their weaknesses, are bidden to rejoice that there names are written in heaven (Luke 10:20). Failings, with struggle, in growing in holiness should not weaken the peace of our being justification and assurance of salvation. It doesn’t matter as much what weakness is in us, as what good; but how we think of them; not what our particular failings are so much as what is the thread and tenor of our lives, for Christ’s dislike for the things that are amiss in us turns not to hatred of us, our persons but to the victorious conquering of all our infirmities[weaknesses].
Some have, after struggles, wondered at the goodness of God that so little and such trembling faith should have upheld them in so great combats, when Satan had almost caught them.
And, indeed, it is to be wondered at, how much a little grace will prevail with God for acceptance, and over our enemies for victory, if the heart is upright.
such is the goodness of our sweet Savior that he delights still to show his strength in our weaknesses.
Excerpt from Works of Richard Sibbes, kindle, Loc. 1884, [Language modernized in places by this site  ours.