The New Testament says,
Romans 8:6 (NCV)
6If people’s thinking is controlled by the sinful self, there is death. But if their thinking is controlled by the Spirit, there is life and peace.
This cannot be any other way, and is the definitive test for whether or not a person is centered in God, whether we apply it to the Islamic militant, the one constantly seeking his own promotion, the non-believer trying to be a “good person,” or the average person who professes Christianity. That is where I am probably most qualified to give an opinion.
I do not think most Christians are living in anything like life and peace. I see many who are so rigid in their understanding of God that they are filled with anger, perhaps even hatred toward, those who disagree with them. I see many others who may not be angry or rigid, but are filled with and largely motivated by fear that their own understanding of God has brought upon them. They falsely think they simply have not progressed far enough yet. The truth is that the seed of fear is present in their understanding of God from the beginning and further progression will lead only to more fear. What is needed is an overhaul. I see many other Christians who live in constant chaos, making bad choice after bad choice, and experiencing all the horrific consequences this will bring into the lives of all who live this way, religious or otherwise.
It is safe to say that religion often brings death, and it does this by getting people focused even more dramatically on themselves after conversion than they ever were before. Ego is tricky, and just when we think we have killed it by converting to this or that religion, it slips into that very religion and poisons it. Thus we might find ourselves feeling prideful over how humble we are becoming, or thinking of ourselves as very different, after all, from the pagans who live around us, taking on a them vs. us mentality. But God is one, and the more we truly know God, the less fracture there will be in ourselves, and the less different we will see ourselves as being from others. Ego and self-interest can, and often does, work its way into the practice of religion and when that happens, religion becomes just one more of the channels we follow to get what we want – only now we perceive that we do it with the blessing of God.
All religion that leaves out the reality of gradual, daily, inward transformation (as contrasted with merely acting in certain ways) will lead to death because it leaves us bound either to dead legalism and rule-following (fundamentalism), or to our own lost selves who appealed to religion in the first place to escape our deadness and lostness (liberalism).
I have very little regard for religion, including Christianity, which is every bit as powerless in itself as any other religion. It takes great effort to clear away the gunk that has accumulated over it and find in it the clear, refreshing, life of God. The best spiritual writing and direction does exactly this.