Or do you suppose it is to no purpose that the Scripture says, “He yearns jealously over the spirit that he has made to dwell in us”? (ESV)
At first glance this verse is a bit confusing. We will have to identify who James is referring to. Which spirit are we talking about? Who is the one yearning jealously? When we come to verses like this it is always a good idea to consider the context of the verses around the one you are studying. Also, find a good commentary or two and see what some other godly men or women are saying.
Let me re-write this verse in a way that you will get more sense out of it. No, I am not re-writing Scripture. I am not a heretic. I just want you to see what the verse is saying. Here goes:
"Or do you suppose it is to no purpose that the Scripture says, "He (The sinful man) yearns jealously over the spirit (the sinful man's spirit) that he (God) has made to dwell in us"?
This is a very damning verse that speaks to the very nature of humankind. The spirit that God placed within us is not naturally prone toward the worship of it's maker. Rather, the sinful man seeks lustfully to place all kinds of pleasures and selfish desires in the way of his own spirit, to entice it towards sin.
We appear to always be in a war. Our sinful nature desires things that are contrary to what the Spirit of God would offer to us. We chase after lustful passions that never satisfy. We place ourselves in opposition to God's plan for our lives. The Apostle Paul was well aware of this battle. I will close today with his words found in Romans:
 Wretched man that I am! Who will deliver me from this body of death?  Thanks be to God through Jesus Christ our Lord! So then, I myself serve the law of God with my mind, but with my flesh I serve the law of sin. (ESV)