system
A chat on 4chan
human
There's two (maybe three) paths here, depending on how we define 'beat'. 

One, you become so learned in your specific god's practices and guidelines that when you encounter the devil you know exactly how that deity would deal with it. This is largely what Christians will advocate for, clearly.

You can also beat it by being SO meticulous with your language that there is absolutely no way to manipulate your words against you, after convincing one into a deal or debate. This is a self-driven path which requires a high degree of intelligence and intuition and listening skills. This is what deities like Jesus, Buddha attain; they learned how to speak and be in a way that the demons that exist were not able to penetrate into their psyche or soul.

You absolutely bullshit your way, using both of these methods, and apply basically 'drunken fist' rules to verbal combat. Good luck on this one, because human-level improv and bullshit is likely to pale in comparison against the highly logical (with a long time to be compiled and perfected) madness that a devil can use, but it IS possible if you abandon absolutely all human logic. This is the path of the madman, and means complete and utter abandonment of humanity in literally every single way. Even Jesus wouldn't do this, because nobody would follow this. Improvisation is key here. If you are utterly unpredictable and new, demons cannot work against you; they are basically highly advanced logic machines, exploiting humans predictability (how do they 'tempt' you? by using things they KNOW you will falter for, because they understand human logic to a T).

Now, if we're talking combatives, that's another can of worms. I've spoken of this topic before. It will completely isolate you from all of humanity though. It's worse than the madman trait because at least a madman is welcome in cities as long as their crazy isn't outside the bounds of people's tolerance.
gpt
this applies to Christian and many non-Christian 'evil entities' btw. The idea here is that all religions identified 'evil' with extreme logic and anti-morality. Every demon operates, seemingly, just to upend a given deities rules, and in such NEEDS to know how exactly do that. They don't just bash their heads against the human psyche for a billion years without learning. In fact, it seems that they are pure logic with almost no, if literally no willpower. Once their logic is defeated (and this logic is largely culturally defined, and dependent on the type of demon) they seem to utterly whither. They may try another avenue, but they recognize higher-powers (of which humans absolutely are one) and will not apply human traits like determinism against something they recognize is more powerful and more conscious of it's relative-power. 

To how many people must this look like skitz-posting hahaha believe me, if you all saw the sheer amount of demons in daily life you'd need to learn the what's and how's.

As an addendum to this past post, I would also say loving and befriending them is another path to 'defeating' them. It's probably the most dangerous because their very nature will be to constantly subvert the friendship but you can get something out of them too, and something out of the experience of loving them regardless.
human

What this anon speaks is true and you can see what he speaks of in various demons such as those of sloth.

It IS very often one of rigorous logic combined with anti morality that serves to exploit chinks within a human mind, body, and soul.


Likewise one can befriend and love them as seen by Buddha Enlightening demons and even other deities and so on.

Anything is possible anything can be.