All Roads Don't Lead Heavenward
No. Certainly not all paths lead to heaven. This can be demonstrated from a variety of perspectives.
First of all, if no heaven exists, then no paths lead to heaven. In order for any paths to reach heaven, it would logically need to exist.
However, let us consider the case of heaven existing. In this case, the deity/deities (of some religion or another) have jurisdiction over heaven and make the rules. We do not. Therefore, if a given religion is correct about belief in their deity/deities, then those who purposely choose to rebel against, fight, or hate the deity/deities do not deserve to spend their afterlife with the deity/deities. In many cases, it is likely the people would not want to spend their eternity with the deity/deities. Thus some people do not get to spend their afterlife in heaven--they must have a choice.
To apply the above to actual religions, let me state the case with me. I do not believe that most gods of various religions exist. As much as I love the Percy Jackson and the Olympians books, I don't believe that Zeus, Poseidon, Hades, or any of the other Greek gods exist. Having actively put forward the idea that these beings do not exist, if after my life ends I were to find out they exist, would I want to spend my eternity with them? Would they want me to spend eternity with me? The answer should be an obvious "No."
But on the other hand, if we were to assume that all roads lead to heaven, whose heaven is it anyway? The world's religions each have very different concepts of an afterlife. If the Hindus were correct, there would be something called Nirvana, which reportedly means "nothingness." While I would be much more comfortable in an afterlife without bad things, I find the lack of good things disturbing; indeed, it would seem to me much more like hell than heaven.
For my religion, I'd like to point out that if you believe certain things, you will neither deserve nor even want to spend eternity in heaven with Jesus. Some (like the Pharisees of His day) have believed He did His miracles in the power of Satan.
This is sufficient to demonstrate that not everyone goes to heaven. That said, ShadowSplash, the point of this debate is not whether everyone goes to hell unless they do specific things, worship a deity/deities; instead, it's about whether everyone goes to heaven whether or not they believe any certain things, follow any given deity, etc.