Thomas Case (Puritan Sermons, 5:524, 525):
Hold fast the models of divine truth in your practice. – A practical memory is the best memory: to live the truths which we know, is the best way to hold them fast.
There are heretical manners as well as heretical doctrines. “Profane Christians live against the faith, whilst heterodox Christians dispute against the faith” [Augustine]. There be not a few that live antinomianism and libertinism, and atheism, and popery, whilst others preach it. Apostates are practical Arminians; a profane man is a practical atheist. Whilst others, therefore, live error, do you live the truth; whilst others deny the gospel, do you live the gospel: “As ye have received” the truth as it is in Jesus, “so walk ye” in it, to all well-pleasing (Col. 2:6; 1:10). Without this, a man forsakes the truth, while he doth profess it: “They profess that they know God, but in their works they deny him, being abominable, and disobedient, and unto every good work reprobate” (Titus 1:16).
Yea, to live the truths we hear, is the way, not to hold them only, but to hold them forth to others; as the apostle speaks, “Holding forth the word of life” (Phil. 2:16). It is a metaphor taken either from fire-lights upon the sea-coasts burning all night; the use whereof is to give notice to seamen of some neighbouring rocks and quicksands that may endanger their vessel: or else from torch-bearers in the night-time; who hold out their lights, that passengers may see their way in the dark. According to which metaphor our Saviour calls true, real Christians “the light of the world, a city set on a hill,” to enlighten the dark world with their beams of holiness (Matt. 5:14). It is a blessed thing when the conversations of Christians are practical models of gospel-truths, walking Bibles, holding forth “the graces” or “excellencies,” “of Him who hath called them out of darkness into his marvellous light” (1 Pet. 2:9).