There are certain things that are always present in the typical, characteristic, Christian experience, and you will find them described everywhere. Take, for instance, the Bible itself: there is a common pattern to all the cases that are described in the Bible, there are certain things that are present in all, and those are the things in which we are interested. Or if you take up the biographies of Christian people or read the lives of saints, you cannot do so without discovering this common pattern.
Certain things are always present, and that is why if we are not aware of these things in ourselves, we are just not Christian. Or take your hymn-book: different men wrote the hymns, but they all say the same thing. There is this common element, this common pattern. The Christian experience is something quite definite, it is quite concrete; that is why a man can really test himself and discover whether he is Christian or not. The New Testament exhorts him to do so, and it is asking of him something that can be done. There is no need for uncertainty in your mind; it can be discovered quite easily. Let us never think of the Christian position as some vague, indefinite, nebulous thing somewhere up in the air. No, the Christian position is a very definite one; it is one of the most concrete things in life.
Adapted from D. Martyn Lloyd-Jones, Out of the Depths (Kindle Edition)