Lightly toast the pita bread and chop it into bite-sized squares, about 1/2-inch each. Place the bread in a large bowl along with the tomatoes, cucumber, chickpeas, scallions, and parsley. Mix the vegetables around lightly to combine. Sprinkle in the minced garlic, red pepper flakes, cumin, coriander, 1/2 teaspoon salt, and pepper. Toss everything together until the vegetables are well distributed and evenly coated with the spices.