Welcome, GBFAN, and thank you for accepting this debate.
Since the burden of proof lies on me, I will have to show how religion is unnecessary for morality.
Let me start with the definition of morality that I will be operating by in this argument.
Morality — a set of personal or social standards for good or bad behaviour and character. (
Cambridge dictionary)
My first argument will be that there are many sources of morality that have no connection to religion, and it is therefore unnecessary.
1. Morality based on reason
Almost 250 years ago, one of the greatest thinkers of all time, German philosopher Immanuel Kant presented his idea of morality that is purely based on reason alone:
Here, Kant says that unless you would wish your maxim (the motivating principle) of your action to become a universal law, you should never act in such a way. This is then easily proven by means of imagining a situation where a person's circumstances can be improved by making a promise known to be impossible to keep. While it certainly might bring about some amount of alleviation in the short term, it is by no means something one could wish to become universal. That is because in a world where nobody keeps their promises, the whole concept of promise is undermined, and therefore the morality of such an action does not hold. This shows how pure reasoning can be used to arrive at a scalable moral principle that can be universally applied while not requiring an external command or supervision to encourage a moral act.
2. Mutual benefit principle
This is a simple but powerful concept, often mentioned by thinkers like Matt Dillahunty, that arrives in a similar place as the first argument and can be best described as follows: If I behave in a socially acceptable manner (not stealing from, taking advantage of, harming or neglecting others), by doing that I will therefore encourage other people to do so and thus being moral and thoughtful of others becomes something everyone is interested in. Here, the focus is on thinking how I would wish others to treat me and then acting in the same way. If I don't want to be stolen from, I shouldn't steal myself and encourage punishment for those who do steal. If I do not wish to be lied to, I shouldn't lie. Thus, this principle, even if all action is based solely on personal interest, provides a sustainable moral framework, again, without any divine intervention.
3. Evolutionary cooperation
In addition to our reasoning capacity that can serve as a ground for morality, there is also an evolutionary element to the matter that explains the moral intuition. Namely, cooperation. Ever since humans began to live in small groups, those who had inclinations to perform counter-productive acts towards their community (such as theft, murder etc.) were less likely to survive on their own outside the group, and thus the genes of the more inclined towards cooperative behaviours were more likely to be passed on and preserved. This explains how humans have a 'built-in' sort of intuitive mechanism, among others, that can lead to moral decisions.
Conclusion: So, we have established that morality can be found by means of reason (namely, the universalization and mutual interest principle), as well as evolutionary processes such as cooperation. Also, as we have seen in these arguments, secular morality stands on both rational and empirical bases, which makes it complete. Therefore, theism can offer a version of morality, but it is not necessary.
I hereby yield the floor to my opponent.
