A favorite atheist challenge is “what evidence do you have for the existence of God?” Summaries of the existing arguments abound, but most people don’t take the time to read even those.
Nevertheless, here is my summary using the framework of the four epistemological methods available to us. These are pretty much standard.
1. Empiricism
Theists (like myself) claim that empirical methods (experimentation and observation) are only good for material entities, so immaterial realities like objective morals and God can not be confirmed using empiricism.
2. Reason
This is one of two primary methods for examining the reality of God. Reason includes archeological and historical data (which are not strictly empirical since they are not directly observed, but must be interpreted), logic, pragmatism, and integration with other systems of knowledge. Classical arguments from logic include the cosmological, ontological, axiological, and teleological arguments.
3. Experience
Classically, this refers to the faculties of intuitionn. • direct perception of truth, fact, etc., independent of any reasoning process; immediate apprehension.
• a function of the spirit rather than the mind
More and conscience (convictions about what is true and moral, respectively). These subjective experiences are common enough that it can be assumed they are basic human functions that have some reliability to them. Alone, they do not prove anything, but they are important evidence nonetheless.
The American founders were referring to the proper use of reason and intuitionn. • direct perception of truth, fact, etc., independent of any reasoning process; immediate apprehension.
• a function of the spirit rather than the mind
More when they coined the phrase “we hold these truths to be self-evident… Objective morals… God.”
Self-evident, also known as properly basic or foundational, means that even though these truths are not empirically demonstrable, our reason and experience definitively confirm them to be true, and those who disagree are not functioning properly in reason, intuitionn. • direct perception of truth, fact, etc., independent of any reasoning process; immediate apprehension.
• a function of the spirit rather than the mind
More or conscience.
4. Authority
This merely refers to authoritative wisdom passed down from our ancestors, either as a sum of their experience and learnings (wisdom literature or science), or in the form of prophetic utterances that supposedly have their authority and origin in God (like holy books). Again, these are not definitive but they are important evidences and data in our quest for truth.
Here’s a longer article I wrote on the topic if you are interested.