There is absolutely no way to condense the answer to any reasonable length. But we will start at the beginning.
- God created the world to be good, just, and a reflection of God.
- Humanity was created to govern this creation.
- Humanity wrecked creation through selfishness, sin, and disobedience.
- God desires to restore creation to its right state.
- Because God desires to restore creation God will restore creation.
- This restoration is called The Day of the LORD and will happen at the close of history as we know it.
- God desires to have humans govern the new creation as they were supposed to govern this creation.
- To begin this process God entered creation in the person of Jesus of Nazareth who has come to unite us to God through his life, death, and resurrection, and by teaching us how we are to operate in God’s world.
If we believe this basic outline, then Christianity is the story of how God desires the world to work and how we need to live to be in accordance with this desire. This means that if this outline is true then Christianity is not simply “one way of living” or “a good way of life”, it is “the way of life”. Christianity is making a claim that it has the truth about the world (inherently all religions even atheism makes this same claim), and it is either right or wrong, if God didn’t create the world or if God did not become incarnate in Jesus then the claims that Christianity makes are false and though there might be some aspects of the philosophy which are useful to humanity there is no need to attach them to the trappings of belief.
Essentially, if we deem Christianity true then it makes every difference to the modern world because it offers us the guide for how we MUST live. notice the word must not should, because life only issues from God and if we live contrary to God we are removing ourselves from life. This is why worldviews matter, there is an inherent truth about the creation and purpose of the world and each worldview claims to have found that objective truth. Logically only one of these worldviews can be right, whichever worldview is correct ultimately understands humanity, in terms of its originals potential, and purpose. For adherents of any worldview (not just religious ones) truth is important. Even a person who claims that truth is relative has started with the basic assumption that there is no purpose to either human existence or the cosmos. The philosophy is that because there is no purpose there is no meaning which allows me to become the author of any meaning I choose to subscribe to my life. [This by the way was according to the Bible the very first temptation humanity was faced with.] The modern notion that religion “adds meaning to life” presupposes that there is no meaning inherent in life. Religions (all religions) say no there is an inherent meaning and here is how we orient our lives to that meaning. Christianity is not an exception to this rule. If Christianity is objectively true then it holds all meaning for human life and modern society.
For more information see C. S. Lewis Mere Christianity,