If one is convicted that OSAS is the truth then they can not at the same time believe it's possible to lose faith, thus really making the question invalid to Knight in the first place. Of course there is no concern for losing something one never had. That theology does tend to lead to a callousness.
Words and actions really don't matter all that much.
Everyone is undoubtedly responsible for their own actions, which includes words.
I trust what Jesus said to be true. He said His disciples are known by their love. And this regarding words.
"...for the tree is known by its fruit. You brood of vipers! How can you speak good when you are evil? For out of the abundance of the heart the mouth speaks. ... I tell you, on the day of judgement people will give account of every careless word they speak, for by your words you will be justified, and by your words you will be condemned." Matthew 12:33-34, 35-36
Words have consequences in this life and the next, and they come from who we are, who is inside of our heart.
If a man on the edge of a cliff hears us say jump, He may. He will be accountable for jumping, we will be accountable for encouraging. Or we can tell him of the Great love we have found and He may come down.
"A soft answer turns away wrath, but a harsh word stirs up anger." Proverbs 15:1