Fair question, at which I struggle for an answer. I take 1 Corinthians 2:14 to mean simply that these things can be sensed in the spirit, but it's very difficult to express in words. I'll try.
The only thing that makes sense to me is the following system of beliefs:
1.) God is perfect. Sin (defined simply as "imperfection") cannot exist in His presence. Because of His holy nature, sin and imperfection would be immediately destroyed.
2.) God loves us and wants our fellowship. Therefore, He provided a way to remove our sin, so that we can enter His presence without being destroyed.
3.) That way is Jesus Christ. We cannot save or cleanse ourselves. We cannot be "good enough" by ourselves, because until this life is over, we are always going to be imperfect. We need Jesus as our shield and protector.
4.) Jesus Christ came to earth as holy God in a fleshly body, to be treated as a sinful, imperfect being. He died as sinful, imperfect beings do, even though He didn't deserve it. This opened up the way to give me what I didn't deserve--an eternity in the presence of God the Father.
Other subtle aspects and doctrines of Christianity, what makes up the differences between denominations and various congregations, I think about as little as possible. Jesus is the way. That's pretty much all I'm capable of making sense of, so I cling to that. Like electronics, acupuncture, dialectical behavior therapy, and other things in this world, I don't have to know *how* something works to know it works. Same thing for Jesus Christ and His salvation.
