The Intellectual Grounds for Belief
For me, the most fundamental component of my belief framework is the strong, intuitive conviction that everything must be here for a reason. This is a form of applying the Principle of Sufficient Reason. Many atheists, while holding to some form of PSR in their daily lives, are happy to simply accept as a brute fact that the Universe just exists and focus on other questions. It would be very unsatisfying to me if the Universe, which is clearly a contingent thing, does not have an explanation for its existence.
(And please don’t ask me why the PSR doesn’t apply to God. If you feel that is a pertinent question, then you haven’t understood my argument.)
Secondly, there are some observable phenomena which currently do not have a satisfactory answer assuming an atheistic worldview. Examples are consciousness, moral convictions, and the structure and order of the nature. Atheists like to propose evolutionary explanations for some of these, but I think they mostly miss the point. (Example: even if consciousness is an advantageous feature to have for an animal, that explains nothing about how consciousness came about in the first place.) Consciousness is especially a big one, since it’s so tied into my daily experience of personal identity, personal will, and what constitutes reality. These features of the universe fit well with my personal intuition of the PSR that I just explained above.
These reasons (and some other arguments for the existence of God that I have chose not to include here) make me favorably disposed towards theism. It is not enough for Christianity. This is where special revelation comes in. I think Christianity is the most well-balanced, convincing, and personally satisfying theistic worldview there is. It powerfully balances the explanatory power of theism with a compelling notion of a God who loves us and desires a relationship with us. Jesus, the God-man, embodies this balance. Christianity doesn’t only demand obedience and submission to God; it gives a good reason for it, namely that God himself has loved us so much that he personally went down, sacrificed himself for us, and challenged us to follow him and spread the word. I think even if Christianity turned to be false, one would still have to admit that it was a really potent idea. Much more potent than the religion of Thor or the Flying Spaghetti Monster.
(Of course, there is also a strong evidential case for Christianity, namely the resurrection of Jesus. But I have already wrote on this topic before.)
The Personal Aspect How Shall I Decide?
But being intellectually convinced of Christianity is not enough. My decision to live as a follower of Christ is not based on a cold, calculating evaluation of the evidence, like one would when evaluating a scientific theory or deciding which stock to buy. It’s at this point that talking about the “evidence” is a misnomer. The evidence has been presented and considered. But you can’t be a Christian to hedge your bets or impress others; at some point you have to be willing to switch to an existential mindset and decide what you want to do with your life. @Patrick talks about “creating” meaning and purpose in our lives. But who or what should I turn to to shape this purpose? And why should I look to them instead of others? Should I just go with the flow of the people around me, with what my friends are doing? Well, how should I choose my friends then?’
These questions are endless, and generate existential crises. They are impossible to resolve in a linear, foundationalist way, because there isn’t any such solution which is clearly the right one. These are very meta-level questions. We are not simply evaluating evidence - we have to decide by what criteria should we evaluate evidence itself. And that’s much harder. As @colewd comments, everyone believes in a sort of coherentism in the end. We decide upon a set of beliefs, live by them and see if that satisfies us personally (not just intellectually). If they don’t, we tweak them until they do. For example, there are many accounts of people leaving a religion because they found it oppressive.
We also find means to validate our prior choices, because nobody wants to be wrong on such foundational and personal matters. One sees this in accounts of people who were former Christians: they join communities of people with similar backgrounds, serving as a support group that validates the choices they just made and supports them going forward. They spend more time hanging out with similar-minded atheists and agnostics instead of religious people, and no longer spend time doing religious activities like prayer, worship, or reading Scripture. They tune into Sam Harris, Richard Dawkins, Sean Carroll, or some other enlightened secular humanist who has something to say about how to live as a personally fulfilled atheist. Of course, people who convert into Christianity do the reverse: they join a church as their support group, start doing Christian things and read Christian books. My point is, deciding on the Big Questions of life is not a purely intellectual decision, because we are not just brains on a stick. Each of us is a holistic, embodied creature with many personal needs and wants.
From a Christ-admirer to Christ-follower
In my own case, at some point in my life, I decided that Christianity was intellectually and personally compelling, and due to a combination of various circumstances, I chose to live as a Christian. I wanted to follow Jesus and become more like Jesus. This decision rippled back out to all aspects of my existence. I committed to being in a church, filled with like-minded people who had the same goal. I prayed and read Scripture. I slowly but surely shaped my thought and filters to fit to this new epistemology. If I seriously believed that a personal God exists and He cares about us humans, then it is not ridiculous at all that sometimes I could see (or at least seem to see) how He works in this world. It goes without saying that I don’t expect non-believers to agree with me.
Thus, for me, my decision to be a Christian is not reducible to a series of special religious experiences (such as a witnessed miracle) that definitively showed the existence of God and compelled them to believe. I am aware that some people do think of their personal Christianity in those terms, and that is completely fine. My own experience is way more complex, as I have tried to summarize here. In the end, both types of people want to follow Christ, and that’s the most important thing. Even though special miracles don’t play a big role in my day-to-day experience of Christianity, in the long term, I’ve seen how I’ve grown and matured in faith, and I think that is way more central to what Christianity is about than constantly having “mountaintop experiences”.
Some Final Remarks: Evidence or Rationalization?
Now, it is true that my family is Christian, and as a teenager, there would have been a social and personal cost to me if I had become an atheist or Muslim or other religion instead. Thus, some people might respond to my testimony with something like the following:
“Daniel was simply brought up in a Christian environment, indoctrinated by his parents and rationalized everything else from there. That’s the only reason he feels any of the ‘evidence’ is compelling.”
Towards this accusation, I would offer two responses. First, despite my personal history, I am currently an adult who is financially independent of my family, and live among people who are mostly secular. I could choose to become an atheist if I wanted to without severe repercussions. Or at least I could just stop being such a fervent Christian and just stay a nominal one, instead of declaring my faith to the world. I know of several people who grew up in a religious family and chose to formally leave the faith the moment they separated from their parents. Yet I chose not to do that.
Secondly, I am unsurprised and unfazed by a such a dismissive response. Your response to this testimony will also be shaped by your prior belief commitments and how you chose to view the world. For some people, dismissing all religious thought as rationalization is their tool to make sense of what is happening. For others, my testimony is an example of the Holy Spirit guiding me to persevere and grow in the faith. Which viewpoint shall you choose? At this point, I have already made my choice, and it has served me well personally. It’s transformed and shaped me into an indelible part of who and what I am. This is why I continue on this path.