It is true indeed that salvation is bestowed by grace and received through faith — entirely apart from works, religious or otherwise. But it is equally true that it costs to embrace the truth and costs even more to stand for it, rather than selling out. This is why Proverbs 23:23 exhorts us to “buy the truth and sell it not”. In this sense we are not to sell the truth. Yet in another sense we are salesmen of the truth, urging men to buy it.
As we do this we find that there are those who would actually seek to hinder men from buying the truth. Yet it is not primarily they who oppose our efforts, but Satan and his hosts.
“FOR WE WRESTLE NOT AGAINST FLESH AND BLOOD, BUT AGAINST PRINCIPALITIES, AGAINST POWERS, AGAINST THE RULERS OF THE DARKNESS OF THIS WORLD [age], AGAINST SPIRITUAL WICKEDNESS [wicked spirits] IN HIGH PLACES” (Eph. 6:12).
This is why God’s salesmen must also be “good soldiers of Jesus Christ” (II Tim.2:3). We must make the glorious message known despite the opposition. We must “put on the whole armour of God” and meet our adversaries with “the Sword of the Spirit, which is the Word of God”(Eph. 6:11,17). When they would shut our mouths we must pray for ourselves and each other:
“…that utterance may be given unto me, THAT I MAY OPEN MY MOUTH BOLDLY, to make known the mystery of the [Paul’s] gospel.
“…THAT THEREIN I MAY SPEAK BOLDLY, AS I OUGHT TO SPEAK” (Eph. 6:19,20; Rom. 16:25, 26).
This, by the grace of God, is our prayer and our resolve. source