Simply, a worldview is how we look at the world. It is the sum total of our fundamental assumptions about "how things are." It is usually used in the context of the greater issues in life. Does God exist? Do souls exist? Are humans special or important? Do we have free will? Is there a moral law? Is evil real? Is good real? Are heaven and hell real places? Can I go to either place? Is there life after death? What exists? How do I know? What is truth? Does God "talk" to us? Can I know it? Stuff like that.
Think of your worldview as a pair of glasses. If you are wearing a "Christian" worldview pair of glasses when you look at the universe then you believe that God exists in three persons and one essence. You believe that souls exist. You believe that humans are special in an almost unbelievable way because we are created in the image of God. You believe that there is a moral law. Good and evil are real. You believe that we have free will and that we make moral choices. You also believe that heaven and hell are real places and that you get to freely choose your eternal destiny. You believe that both material and immaterial things exist. You believe that reason applied to empirical evidence is the ultimate truth standard. You believe that truth is that which corresponds to reality. You believe that God speaks to us through nature (reason and evidence) and His Word (revelation) and that they are never in conflict. (How could they be?) You believe that purpose and design are all around us and that we are the objects of His purpose. You see the glory and majesty of God in the intricate design and unimaginable vastness of the universe. You believe that we can know what He says.
From this, certain things necessarily follow. If God exists and He is as we typically think of God, then we had better not ignore Him. If we are created in His image (thinking, intentional, moral, sensing, feeling, rational) then every human being has great value, regardless of skin color, eye color, hair color, nationality, sexual orientation, political preference, religious background, IQ, talent, gender, and every other way that we categorize ourselves. EVERY human being has intrinsic value because every human being is created in the image of God. (If it's actually true, that is.)
It also then follows that every human being, created in the image of God, has the same fundamental value (priceless) and therefore has the same rights and responsibilities as every other human being. It follows that we would want to go to heaven (eternal bliss with our Creator) rather than go to hell (eternal torment away from our Creator). We'd want to know how we could do that and hope that we could actually do it. It seems that we would be inclined, at least, to treat other human beings as if they were intrinsically precious since we know that they are. We would understand that it is wrong to take advantage of those that are weak, or less able to fend for themselves, whether by lesser physical, mental, financial, or other resources. Perhaps, most importantly, we would know that we are ultimately ACCOUNTABLE for our thoughts, words, and deeds. We might feel motivated, on occasion, at least, to do the right thing. We may even feel an obligation to be good stewards of the planet God has given us to live on. Who knows? Stranger things have happened. We might think that God had actually created us for a purpose and that we would want to fulfill that purpose. This is not an exhaustive list, by any means, but I trust it is detailed enough to give you a sense of how a Christian worldview would play out in life. Or should.
On the other hand, if we had a materialist worldview, we would believe different things about the universe we live in. If we had on "materialist glasses" we would see things in other ways. For one thing, we wouldn't believe that God exists. (God is a "spirit" and spirits are not real by a materialist ontology.) Minds or souls do not exist. There is no purpose or design or point to the universe. Everything can be explained by physical laws. (After all, if everything is matter and energy and they are governed by physical laws, then EVERYTHING can be explained in terms of the laws of physics.) Human beings are just another form of life, accidental and meaningless in the vastness of the universe. We are here strictly by chance and we have no more value than any other form of life. Say a cockroach or a lizard or a weed. They are all fundamentally the same. They are merely different outworkings of neo-Darwinian evolution. Mindlessly chugging along it produced everything from human beings to bacteria and everything in between. We believe that survival and perpetuation of the species is all important. We know that there is no such thing as a moral law. Laws are immaterial creations of mind and since minds do not exist neither do laws. Or information. Or design. Or purpose. There is no such thing as free will. How could there be when free will is immaterial and would somehow not be beholden to the laws of physics? How do we explain information in any coherent way? Information requires contingency but the laws of physics provide no contingency. I will spend a fair amount of time on this.
I'll be first in line to say that if the materialist worldview is true then it is and so much the worse for us. Believing something that is NOT TRUE (Christianity, in this instance) is foolish and pathetic if the materialists are correct. No matter how much we might want it to be true, or how much better we think the world would be if it were true, it only matters IF IT IS TRUE. On the other hand, if the materialist worldview is false (I think we've seen that already. Although I will gleefully continue to point out the absurdities, contradictions, and patent falsehoods as long as I draw breath.) what a ridiculous thing to believe. Can you imagine anything more hideous? To reject truth. To spend eternity away from your Creator by your own choice. To spend your whole life thinking that you are no more important than rocks, or dirt, or slugs. To think that there is no meaning or purpose AT ALL. To think that nothing that you do while you are "alive" EVER REALLY MATTERS. How breathtakingly stupid and depressing is that? Well, I hope we'll see in the days to come.
I suspect that you are already beginning to see some of the inherent contradictions in a materialist worldview. How can I say that everything is governed by the laws of physics when my fundamental belief about the nature of the universe denies the existence of those laws? How can I have choices when there is no free will? How can anything be wrong if there is no moral law? How can purpose of any kind exist in a purposeless universe? Why should I pay attention to any social conventions? Why should anything matter to me, including me? Why would reason exist in a purely material universe? Is reason comprised of fermions and bosons? Do the four forces of nature affect reason? These are the kinds of questions that need to be definitively answered.
Meanwhile, let me put in another plug for reason. Just like there are causes and effects in the material world, there are causes and effects in the immaterial world. Ideas matter. Ideas eventually play out in public ways. Remember Nazi Germany if you think ideas don't matter.
It seems fairly obvious to me from the discussion above that above all, what we need to demand from our worldview, is that it give us a true picture of reality. Does God exist? Is Jesus the Son of God? Are we special in any way? Are we merely random collections of sub-atomic particles suspended in really cool bags of water? Does any of this matter? Of course it does. Read on...