welcome-to-heaven-loser
Explanation
The Joke
A newly arrived soul is greeted at the gates of heaven with "Welcome to heaven, loser." When the soul protests that this is mean, the heavenly gatekeeper (depicted as a large bearded figure, possibly Saint Peter or God) explains that heaven used to get "righteous psycho warriors for God" and "iron-willed martyrs or mystical ascetics," but now all they get are "dorkwads who spend all their time at a game console riding imaginary unicorns and sprinkling virtual pixie dust, thus eliminating all the spare time required to get busy with super cool wicked lifestyles."
The gamer soul protests: "I am not just playing video games. I am appreciating logic systems presented in the form of stories." The gatekeeper then notes that the gamer cannot fight anyone because "due to a lifetime of gaming, your coordination and strength are concentrated entirely in your thumbs." The gamer offers to fight anyway, saying "I'll thumbs you real hard, man!" and is told to calm down and join the other losers in heaven.
The Humor
The comic satirizes the idea that modern people who end up in heaven would be very different from the heroic, ascetic, or martyred figures of religious tradition. Instead of sword-wielding crusaders or self-denying monks, heaven now has to accommodate people whose greatest moral achievement was being too busy playing video games to sin. The gamer's attempt to intellectualize their hobby ("appreciating logic systems presented in the form of stories") is a recognizable defense that gamers use in real life, made funnier by the context of trying to impress a heavenly authority. The physical comedy of someone whose entire body strength resides in their thumbs trying to pick a fight adds a final absurd touch.
References
The scene at heaven's gates is a riff on the traditional Christian imagery of Saint Peter greeting souls at the Pearly Gates. The comic's mention of "psycho warriors for God" likely references historical figures like the Crusaders or biblical warriors, while "iron-willed martyrs" and "mystical ascetics" refer to the saints and desert fathers who are celebrated in Christian tradition for their extreme devotion and self-denial.