Much that passes for Christian decision making in modern Evangelicalism strikes me as a mixture of lazy moral reasoning and illegitimate efforts to discern those "secret things" (Deut. 29:29) that God has never promised to reveal to us. Scripture has much to say about the way we approach important decisions in our lives. It tells us, for instance, to take our time in making decisions (Prov. 21:5), to consider all the relevant facts (Prov. 18:13), to seek wise counsel from others (Prov. 11:14), to make choices that will maximize, not undermine, our ability to love God and love others (Prov. 10:9), to aim at God's glory in all our decisions (1 Cor. 10:31), and so on. It establishes boundaries for what's acceptable with regard to certain decisions; it tells us, for example, not to be unequally yoked (1 Cor. 6:14), a moral imperative that bears upon, say, decisions we make relative to marriage. It seems to me, however, that such biblical advice about decision making is regularly trumped in modern evangelical circles by simplistic appeals to what God is "leading" one to do, perhaps with justification provided by significantly misinterpreted and misapplied biblical texts (e.g. Rom. 8:14).
Consequently, I find myself assuming a posture of wariness whenever I hear Christians speak of determining "God's will" for their lives. Scripture, in keeping with our finite human perspective, presents God's will to us as two discrete realities. It describes, firstly, what theologians refer to as God's preceptive will, which encompasses all God's moral commands to us (see e.g. 1 Thess. 4:3). It describes, secondly, what theologians refer to as God's decretive will, which encompasses everything that God has determined to do in relation to us and the world, and so comprises every created reality and event (see e.g. Eph. 1:11). God's preceptive will for us is readily available to us in Scripture. God's decretive will is fully known only to him, though he reveals certain aspects of his decretive will to us in certain times and places, in keeping with his purpose. So, for instance, Christ's return constitutes one yet to be realized aspect of God's decretive will that, by virtue of God's revelation of said future event, I can count on with absolute certainty.
When Christians speak of determining "God's will" for their lives, they rarely, so far as I can tell, mean by that efforts to determine God's preceptive will (which, quite frankly, they would do better to concern themselves with). They typically, rather, refer to efforts to determine God's decretive will, specifically as such infringes on their own personal lives. Whom should I marry? Where should I go to college? Should I take this or that job? These are the questions that typically prompt efforts to determine "God's will." But Scripture never invites us to pry into God's decretive will. In fact, it sharply discourages us from doing so (Deut. 29:29). Scripture invites us, rather, to frame our lives according to God's preceptive will, and to exercise wisdom and good decision-making principles (see above) when faced with life's multitude of choices.
I find myself similarly uncomfortable with the language of "open" and "closed doors" that regularly features in Christian talk about decisions. I realize the language itself is biblical (cf. 2 Cor. 2:12), and perhaps some Christians use it in more or less the way that Paul, for example, used it. But, in doing so, they forget that Paul, as an apostle, was the recipient of unique revelation and unique direction from God, and that, as a result, his experience will be decidedly un-analagous to our own at significant junctures in life. The example of an apostle (or other holder of some extraordinary office in Scripture) shouldn't, in my judgment, necessarily be considered normative when it comes to questions of decision making or navigating the relationship between divine sovereignty and one's choices in life. The balance of Scripture, it seems to me, doesn't encourage us in efforts to discern God's decretive will for our lives by providential events (i.e., open or closed doors). Sometimes a closed door simply needs to be pushed on harder. Sometimes an open door needs to be passed by. The wisdom and biblical principles that govern decision making should always take precedence over providential "signs" that Scripture never bids us decipher.
The posture of Paul and Silas relative to one literally (and by literally, I mean unfiguratively) "open door" might prove instructive on this point. In Acts 16, Paul got himself and Silas into hot water in the city of Philippi when he cast a demon out from a young slave-girl and so angered her owners who were profiting financially from her demon possession. Paul and Silas subsequently endured a beating at the bidding of Roman magistrates and were placed in prison. During their night in jail an earthquake occurred, and "immediately all the doors were opened, and everyone's bonds were unfastened." Hit pause and put ourselves in Paul's shoes for a moment. How many of us, I wonder, would have interpreted the open prison doors as a clear sign from God that he intended us to escape an unfair imprisonment administered by the hand of suspect secular authorities? But what did Paul actually do? He remained in prison until daybreak (a fact that led to the jailer's conversion). He subjected himself to the governing authorities instituted by God in that particular city, just like he tells us to do elsewhere (Rom. 13:1-2). He applied some solid moral reasoning to his situation and determined that his proper course of action was to let justice run its course (even though "justice" in his specific situation seemed decidedly unjust).
Paul's passing over the "open door" in Philippi might serve, I think, as a lesson to us all. Rather than seeking to decipher what God would have us to do in given situations by recognizing and interpreting various "signs" (open doors and otherwise), we should seek to familiarize ourselves more fully with God's preceptive will in Scripture. There is ample guidance in Scripture for how we should live our lives. There's also, relative to some of life's most difficult decisions, ample freedom to choose various paths provided one let's his/her choice be governed by the biblical principles that should inform decision-making per se. We can exercise that freedom with joy, confident that all our decisions fit into God's decretive will.
Or, as Augustine put is so much more succinctly and eloquently sixteen centuries ago: "Love God, and do what you want."