Demian....
I hear you points. And they are all valid questions. I think your a logical thinker, and may I suggest reading The Case For Faith, by Lee Strobel. It handles most of your questions decently, using a logical mind. And I think God would have one set of ideology. Keeping to one faith, and one mind is important in society as in business, or anything. A good mix of constructive ideas to solve a problem is important, but multireligious views on a problem are not necessary. You cant have the CEO of Clear Channel in with the SiriusXM board meeting can we. Just as a christian church shouldnt allow an athiest to go around corrupting their childrens minds(as they see it, remember, this a community of equals and peers that have decided their own rules). If a person does not want to abide by these conditions, they should leave, not try to change the whole group.
Here is how a biblical christian would go about his life.
Farm his land, have his kids work the farm, and animals to survive. If a neighbor needed something, or to trade, he would do it. Period. They wouldnt use each others land, or seek to control the other. They would get along wonderfully. If a problem like water supply arose, they would all work together with one mind, and spiritual body, and solve it for teh community. If someone wnats to change this thinking, he should be allowed to leave, and go away(probably come back with a gun later to rob them, and you see where tolerance gets you). Now this makes community leaders important to not abuse this power, but they will, and thats why the community must handle it as a whole. To never allow one person too much power. And if a community keeps their consequences local, and inform, society can function like a well oiled machine. If you have growth in your family, go find other lands, go explore. Tons of land for everyone on earth. Too much land. We huddle in cramp cities, polluting on each other instead. Thats not how christians would choose to live. You huddle in cities for protection, and thats about it. Otherwise, they only lead to the constant contact between many humans that is never good for the status quo. Biblical way of living is not a bad way to go.
If over population becomes a problem, Im sure God thought of this and has a solution. Have a little faith.