There have been a number of attempts to argue for the existence of god from the standpoint of reason. Many of these arguments have a long history and most would have been familiar, at least in principle, to the ancient Greek philosophers. As you might expect, there is a wide diversity in philosophical sophistication amongst the various attempts. Some are blatantly silly and some try to confuse with mind numbing, begoggling (is this a real word?) sophistry. There is much redundancy and arguments current two thousand years ago have been repackaged and labelled for the modern mind and audience.
Thoughtful Christians have seen through the sham that is 'faith'. To believe anything on faith is to believe in a concept in the absence of evidence. Often faith is considered a positive virtue of which the possessor should be proud. However, faith stands in opposition to reason and offers no rational basis for belief. Indeed, on the basis of faith, you can convince yourself of anything, no matter how implausible the notion. Theologians crave intellectual respectability and are driven to find coherent and logical explanations for the existence of god. Many theologians consider theology as a legitimate branch of philosophy. I disagree. Good philosophy should be about following logical reasoning to uncover the truth, no matter how unpalatable or counter-intuitive the conclusion; the destination should be unknown. Theology already knows the answer and therefore argues back from the dogmatic conclusion to find the strands of 'evidence' for its conclusion. This is not philosophy as I know it.
Often explanations are proposed as logical or appealing to the intellect when they do no such thing. A particularly good example of this approach is 'Pascal's Wager'. Blaise Pascal, the eminent 17th French philosopher, mathematician and scientist formulated a rather cynical appeal to self-interest. The wager masquerades as a petition to reason, but is actually a cunning appeal to psychology and to the psychology of intimidation, at that. But let us not be beguiled by the scientific credentials of the proposer. In this spirit let us consider a brief overview of Pascal's original argument.
1. Pascal asserts that god's existence or non-existence cannot be determined by
2. Therefore, it follows that the wise thing to do is to live as though god exists.
3. If god exists you have everything to gain: entry to everlasting life.
4. If god does not exist you have lost nothing.
5. However, if god does exists and you do not believe you lose everything and enter
6. So, if we consider the two options, the rational choice is to believe. Perhaps living
as if in faith may actually lead to true belief, eventually.
Firstly the assertion that reason cannot distinguish between theism and atheism is plainly false. The onus of proof lies with the believer, not with the unbeliever. If god cannot be rationally demonstrated then atheism wins by default.
The 'wager' is a thin disguised attempt at browbeating and frightening the participant: Believe in god, or else. This is morally repellent and indefensible.
Although not explicitly stated, Pascal is referring/deferring to the Christian god and specifically the Christian god of Catholicism. This follows from Pascal’s upbringing and cultural milieu. If he had been raised a Muslim he would have been referring to Allah. Humans, over their history and pre-history, have worshiped a bewildering showcase of gods. This neatly brings me to an important point. Assuming that a very large number of gods have been revered and if we are to accept the principle that they are mutually exclusive, then the possibility of choosing the ‘right god’ is going to be of utmost importance but virtually impossible (tis a matter of simple probability). Therefore, it is unlikely that we would adhere to the right deity thus securing the enmity of the one true god(s) whoever that might be.
An important attribute of many gods and especially the Abrahamic gods is their empowerment and the attribute of omniscience. In other words, they know everything about everything. Thus, it would be impossible to hide your true beliefs from such a god and your cynical sham attempt to fool an 'all knowing' god would be to no avail. Insincerity is no doubt a cardinal sin and therefore will earn you a one-way ticket to the 'hot place'. Granted, lesser gods such as Zeus and Woden may not be so talented. Choose your god wisely. Pick a lesser deity and you might get away with it, perhaps.
There are other objections to Pascal's Wager but I'll not belabour the point. It is a terrible argument and hardly worth the intellectual effort required to refute it. Educated Christians are aware of the proposal's obvious flaws and it is rarely trotted out as a serious proposition except in instances of extreme desperation or frank stupidity. But then Christians, especially of the fundamentalist variety, can be very, very, dim.