Israel was to be a source of blessing to the nations, but to the extent that required their cooperation, it seems they mortally botched the job. Still, God in his grace has made a blessing of them in spite of themselves, and they will be an even greater blessing in days to come.
But with proximity to God and the burden of bearing testimony to him in the world came tremendous risk and tremendous cost. As a result of the curses bound up in the Law of Moses, Israel has spent more time in the penalty box — dispersed throughout the nations or subject to the world powers of the day — than it ever spent at the top of the heap. David's reign and Solomon's were exceptions to the general rule of Jewish experience.
So was God for or against Israel? The answer is not that simple.
Thus, when we come to the story of Naaman the Syrian leper it should not surprise us to find him described as "a great man with his master and in high favor, because by him the Lord had given victory to Syria".
Victory over Israel, among others.
For a time at least, it appeared God was on the side of the Syrians rather than the Israelites, a fact confirmed by the status of the little Hebrew girl carried off in a Syrian raid who now served Naaman's wife. Syria probably wasn't her first choice of destination and servanthood was probably not the life she had imagined for herself. Meanwhile, God was blessing her Syrian master and giving him victory over her very own family and friends, and this despite the fact that Syrians worshiped false gods and were in other ways far from ideal.
That little girl may well have said in her heart, "God is against us." It would have been hard to argue based on the evidence in front of her.
God has his own plans and purposes throughout history, and they are often opaque to us. "I have loved Jacob," says Jehovah, "but Esau I have hated." (God is speaking nationally here, not about his attitude toward individuals.) And yet the "love" that God lavished on Jacob frequently resulted in his children being smacked around by other nations. Likewise, there were times when Esau's children seemed to be doing very well indeed.
Many of us have strong opinions about these things, but few are based on an intelligent perusal of the evidence of scripture. You simply cannot read backward from the historical results of human conflicts to draw conclusions about who had the favor of God at any given point in time.
God's general providential kindness can make it appear at times as if he favors the wicked, while his stern paternal discipline can make it appear as if he has abandoned his own children.
This pattern is so well established that I marvel at the ability of Western nations throughout the centuries to portray themselves as spiritual descendants of Israel or to presume that God owes us anything when we go to war. If it was God that enabled the Allies to rid the world of Adolf Hitler, on what basis did he tolerate the predations associated with the Caesars of Rome? Were there no Christians in Germany in WWII (of course there were), and how did God feel about them? (For that matter, how did they feel about themselves?) Better question: did God cheer at Hiroshima and Nagasaki?
Let's not presume to know what God has not specifically revealed.
Either/or. Good and bad. For or against. Ones and zeroes. Binary.
The commander's answer was non-binary, and most of God's sovereign dealings in history are equally complex. We are impressed by street jugglers, but imagine keeping thirty billion balls in the air at the same time. That's about what the sovereign God is doing at any given point in time. No wonder his ways are called inscrutable.
In such an environment, having the favor of God may not translate into present victory in front of the world, just as those whom God is against may not experience any immediate and obvious distress.