I certainly believe that God opens and closes doors at times, but I also wonder if we rely too much on this as the primary (or only) factor when seeking God’s direction. My fear is that an approach which is over-reliant on 'open doors' may be under-reliant on the hard work of prayer and spiritual discernment.
Consider the 'open door' that was presented to David, not once but twice.
When he was on the run from a vengeful, murderous King Saul, David had the opportunity to eliminate his adversary. The first time occurred in the cave where David was hiding with his men (1 Samuel 24), and the second when he snuck into Saul’s camp (1 Samuel 26). Both times, his friends identified this as God "opening the door".
In the second instance, Abishai said, “Today God has delivered your enemy into your hands” (26:8). Both times, even though the door appeared to be open, David knew this wasn’t God’s will. He responded to Abishai, “Who can lay a hand on the Lord’s anointed and be guiltless … the Lord himself will strike him [Saul], or his time will come and he will die, or he will go into battle and perish” (26:9-10).
Even as David was confronted with this golden opportunity and the pleas of his advisors, he drew on a deeper reserve to answer the question, “What would the Lord have me do in this situation?” His high view of God and understanding of God’s commands formed a solid foundation for his decision.
This is a vital lesson for every believer to heed. Not all “open doors” are created equal. Some truly reflect the hand of God, showing us the way that He wants us to go. Others may be temptations that masquerade as answers to our prayers. The only way to distinguish between the two is a life that is anchored in Scripture and prayer. It requires a willingness to slow down and seek the Lord rather than rushing through an apparent 'open door'."
excerpt from a blog entry written by Mike Bonem