What are the reasons for and against studying other religions?

I think it can definitely provide a better understanding of ones own field by studying other fields.

Let me give you an example from my own life. I work as a physiotherapist. Physiotherapists on e.g. clinics and hospitals work closely together with nurses, ergotherapists, doctors and other healthcare professionals. Working with other professions has taught me a lot about where the "lines" of my own profession go to. What my territory is. It's important to know so one does not cross a line and begin to do nurses work for example.

In the same way i experience that after having gained a better understanding of the Dhamma through study and practice that when reading or hearing about other religions that it serves to enhance my own understanding of the Dhamma by making the lines sharper and the doctrines stand out more clearly. (I'm not myself actively using this method of studying other fields. I just occasionally bump into other religions when watching debates or reading buddhist litterature where there are references or comparisons to other religions).

In a way one works "backwards" when using the method of studying other fields in order to make one's own territory more visible and understable. It can be a good method to use but i think it requires that one has a good understanding of whatever topic one wants to understand better (in our case, the Dhamma). Also it's time-consuming and might limit ones own time to practice.

When i first began with Buddhism i think it would have mudded the picture if i had also studied about other religions at the same time. So based on my own experience i think one should acquire some level of experience before using this method of studying other fields.

I am not Buddhist, but from what I have heard from them, my experiences are sufficiently applicable to be worth voicing here.

I have found great value in studying religions that I do not necessarily believe in. I find it to be a very powerful way to learn from a culture that is very different from my own. In particular, I have found it very effective at highlighting causes of suffering in my own life. The world is an amazing and beautifully diverse place. We have found many ways to live. Many things I was brought up to assume were simply "the way humanity acts" have been shown to be very culturally specific as I study how other cultures work.

As an example in my own life, I have been raised as an American and thus naturally raised to believe in the "equality" of the sexes. Exploring other cultures, I found that the other cultures did not always have what I would call "equality." Studying the religions of these cultures helped me understand how a society could be "good" without equality of the sexes. At the end of the journey, I identified that it was not my fellow cultures that were wrong, it was that my personal definition of "equality of the sexes." My concept of what that phrase could mean was too rigid. Studying other cultures which have succeeded with different meanings helped me widen my opinions. I now hold a wider belief (preferring the word "incomparable" over "equal") which helped me elevate above self-inflicted suffering caused by my overly rigid definitions.

However, there is a difficult counterpoint to this. Studying other religions is an easy question. However, some things cannot simply be studied in isolation. They must be lived. For these things, I recommend not seeking any carte blanche directive. Your life is too important to sign a blank checque. Seek those in your life that you respect for guidance on such things. It is my belief that much of the richness of life is found by experiencing contrasting worlds, but it can be difficult to do. It is easy to blur the worlds together, and miss out on the most important part of both worlds. This is why I recommend seeking guidance from those you respect on such activities. They may be able to help you set yourself on a path which gains as much as possible from the interaction without doing harm to either group, nor yourself. However, there's no one way to do it. Those in your life can help you find your way to do it.

It depends on the individual. I've heard several people say it would be too confusing or wasteful. The analogy offered in Advaita Hinduism is that it is far better to dig one deep well than several shallow wells.

In my personal experience the opposite is true, much to the chagrin of some spiritual friends and family.

We must each obey whatever is our reality. My reality was to reject at an early age the style of Hinduism I was born into, mainly for its unthinking rituals and corruption, and explored Catholicism and then Communism, and Socialism, looking for a means to end human suffering. I settled on agnosticism and atheism-lite with an emphasis on science and technology before seeing that it was hollow too, and riddled with the same rites and rituals and corruption as every system I had encountered so far.

I finally broke into a true form of spirituality when experiencing the spirituality of mountains, rivers and forests. They allowed me to experience the reality of my own body, they allowed me to see that reality was dependant and conditioned. They opened my eyes to some of the same truths as the Buddha speaks of, which left me utterly confused or disillusioned with samsara and forced me to set out on a quest for unconditional freedom guided by philosophers like Thoreau, and Jiddu Krishnamurti.

Stumbling across Buddhism I found a lot of familiar patterns and was impressed with the unquestionable wisdom of the Buddha and decided to stay there a while. Soon enough I found such experiences were also to be found in other religions, like the Hinduism I had abandoned.

In time I saw that the labels didn't matter - whoever had experienced the true essence of reality, had expressed it in their religion, and I saw that the truest scientists like Einstein, and spiritual masters of various religions had experienced the same oneness of creation that I was being exposed to. I don't think Buddhism or Hinduism or any ism has all the answers. The answers are all around us and not within a book.

Any system will be laden with corruption and rites and rituals, it is inescapable. Thus the answers are not in systems, but in a direct dance with reality.

I've settled on Buddhism and Hinduism as the places today to dig my well, but I am not attached to them. It's just a vehicle - not my destination.

From my personal perspective I think it can be extremely beneficial and everyone should be encouraged to study the doctrine and practices of many religions. Even though I grew up in Sri Lanka for 17 years I was never a Buddhist and I dismissed Buddhism as just another religion. I used to be a very devout atheist, aspired to become a theoretical physicist, and had no interest in anything that even remotely resembled religion. While I was studying in Australia and the US I was exposed to a variety of different religious and philosophical traditions. It allowed me to gain an understanding of why different people believe what they believe, what impact these traditions have had on the cultures that adopted them, how different belief systems introduce bias not only at the level of the individual but also at the societal level, how certain biases extend across space and time, and ultimately gain an appreciation for the Dhamma that I otherwise wouldn't have been able to achieve. Now it's only a matter of time before I go forth from home into homelessness.

In terms of general knowledge, it can be helpful to be familiar with the religions of the world on a basic level and there are many books which compare the world's religions in an easy format such as The Handy Religion Answer Book. Reading a book such as this gives an interesting glimpse into the vastness of the the world's religious traditions.

Studying all or many of the world's religious traditions on an in depth level however, would take large amounts of time and effort which could take away from Buddhist practice. As people familiar with Buddhism, we can probably easily appreciate that even within a single religion there can be vast difference in practice and beliefs and to study multiple religions in depth would be a major undertaking.

Intention is everything. An intention to add a bit of general knowledge about a subject or to confirm that your current religion and practice is right for you may be wholesome. An intention to compare your own religion and practice against others in a conceited way or to avoid a tough part of your own practice by busying yourself with endless study could be not-so-wholesome.

When preparing to leave the religious tradition I had been born into, I read a general book comparing religions and it was helpful for putting things into perspective. But, using the example of reading about meditation vs practicing meditation, one doesn't get a true sense of what a religion consists of by reading about it.