A pregnancy is a time filled with the anticipation of joy. Our cultural image of the future father pacing in the waiting room paints that anticipation and anxiousness well. Kandice and I witnessed this recently when some friends of ours went through the stages of pregnancy; for our friends it seemed like each day ushered in a new level of anticipation and expectancy until the day of birth. Somewhat ironically James uses the language of birth to describe sin in our lives, "But each one is tempted when, by his own evil desire, he is dragged away and enticed. Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death" (James 1:14-16). In the above passage James gives us a picture of the lineage of sin--how it can lead to our ruin. More than that though I think James wants to use the language traditionally used to express "joy", "expectation", and "eagerness"--the diction of new birth--to unveil the motives of our hearts when we commit sin.
Tim Keller mentioned one time in a sermon of his that when the Bible says "evil desires" the literal translation means: "over desires". That is, it isn't that I am desiring something 'evil', in and of itself, but that the ratio of desire is off: our desire for sex, money, power, intelligence (to name the big ones) outweighs our desire for God. They our overly desired.
We have such an expectancy with our sin, or over desires. We hope that they will give birth to joy. Instead they are far worse than being merely still born--they attack us. They are not just empty but they begin to tear us down. "Then after desire has conceived it gives birth to sin, and sin when it is full grown gives birth to death" (James 1:15). All our expectancy and anticipation in the face of sin is bankrupt. It's as if I invested everything I owned into a company that collapsed days after. The anticipation leads to destruction. We try time and time again to manufacture joy by following our over desires--our "fashioned idols". But there is only sin--then death.
Fortunately James gives us words of refuge. "Don't be deceived, my dear brothers. Every good and perfect gift is from above coming down from the father of lights, who does not change like shifting shadows" (James 1:16-17). We should not confuse truth with lies, while our over desires fill us with anticipation and hopes of joy only to destroy us, "the Father of lights" gives us "perfect gift[s]" that grow us into the person of Christ.
Something to be thankful for.