The Four Noble Truths are neither path nor gateway. They are exactly what they say they are, truths. Religious truth is also known as dogma. Dogma is how a religion wants you to see the world.
The core dogma of Christianity is threefold, should be quite familiar to you. First, the deity of Christ, then his death and resurrection, and finally salvation by grace through faith alone. If you don’t believe in these three things, then you’re not a Christian. These three things have been debated over and over by theologians for over a thousand years, church as an institution is specifically a place where you are to go to resolve problems.
Similarly, if you don’t believe in the Four Noble Truths of Buddhism, then you’re not really a Buddhist. Only, in the West, you don’t get a church on every corner staffed with people to help you understand what Buddhist dogma means or how you’re supposed to believe. Instead, you have to rely on the materials produced by the self-help industry. Some of it is better than others.
So let’s go through the Truths, shall we?
The first one is dukkha, most commonly translated as “suffering,” but some people say that it’s better translated as “pain.” Now, right off the bat we get right down to one of the things that make being a Western Buddhist hard, the necessity of translation. So is dukkha suffering or pain?
This stuff is exceedingly specific, and the debates about this stuff that settled it so long ago happened in other languages. Dukkha can also be translated as “unsatisfactoriness.” Well, with those three words in mind, you can get a somewhat clear picture of there being a scale from small unsatisfactory dukkha to the intolerable suffering dukkha.
The second one, samudaya, is somewhat different. It refers to the origin of dukkha. The Wikipedia page for samudaya redirects to the Twelve Nidanas, which I suppose is supposed to mean that Wikipedia considers them equivalent concepts, let’s just roll with that. The Twelve Nidanas are, in order, Avijja, Sankhara, Vinnana, Namarupa, Salayatana, Phassa, Vedana, Tanha, Upadana, Bhava, and Jati. These form a chain, it is asserted in Buddhism that each of these links has a primary causal link with the ones it is connected to.
I could provide the translations for the Twelve Nidanas here, but honestly it wouldn’t do the answer a whole lot of good. All of this stuff arose in exactly the same way dogma arises in Christianity. Some old dead people a long time ago wrote some books they took very seriously, and other old dead people who also took them very seriously spent a lot of time interpreting them and arguing about them. The fact that they argued so much over them is their strongest claim to truth. But let’s move on, I have two more truths to get to.
Nirodha mostly just states that it’s possible to progressively reduce and eventually eliminate dukkha.
Finally magga states that there is a path to liberation. What’s the path? Depends on the tradition. The Noble Eightfold Path is one of the oldest but you can read the specific Wikipedia page on Buddhist paths to liberation to get a sense for how wide this particular dogma is. I guess you can say in a sense that the only thing magga really means is that there is a path, rather than defining an actual path.
What do I think about all this? Well, when you realize just how complicated it all is, and how all the infrastructure is all the way over there in the East, and how religious meta-truth often seem interchangeable, Buddhists want you to love others, so do Christians; you really don’t find anything too special about Buddhism. It’s well, a religion. It’s too big for you to really understand without becoming a theologian.
Ultimately I think anyone looking for a religion to follow should look to the one they grew up with first. You don’t have to become a Christian theologian in order to get meaning out of it. You grew up with it, steeped in the culture, in a way you could never get with Buddhism.