What does it mean for Satan to 'enter into' someone? It's more than just a bad thought or a moment of weakness.
The phrase 'Satan entered into Judas' (εἰσῆλθε) suggests a powerful, invasive influence. In the Gospels, this verb is often used for demons taking possession of bodies. Here, it signifies Satan seizing control of Judas's inner being, escalating his internal desires into decisive action.
It wasn't that Satan created a new evil in Judas, but rather that he amplified Judas's existing flaws – particularly greed – to a catastrophic level. Satan works by exploiting our native passions and turning them towards destruction. This isn't about being forced to act against your nature, but being led to act out your deepest, darkest tendencies.