Lord willing

Key verse
John 3:16 - For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

James
Where's the connection between saying that you will do something, Lord willing, and knowing the good you ought to do and not doing it?  In 4:17, James writes "Anyone, then [suggesting a connection between what he previously said], who knows the good he ought to do and doesn't do it, sins."
Here's something from Barnes' notes:
        The particular meaning then would be, "that he who knows what sort of views he should take in regard to the future, and how he should form his plans in view of the uncertainty of life, and still does not do it, but goes on recklessly, forming his plans beastingly and confident of success, is guilty of sin against God." Still, the proposition will admit of a more general application. It is universally true that if a man knows what is right, and does not do it, he is guilty of sin.  http://bible.cc/james/4-17.htm