In a large pot, heat olive oil over medium heat.
Add the chicken breasts and cook for 4–5 minutes per side until golden brown.
Remove the chicken from the pot and set it aside.
In the same pot, add the chopped onion, garlic, and red bell pepper.
Sauté for 5 minutes, until the vegetables are soft and fragrant.
Stir in the oregano, cumin, paprika, thyme, salt, and black pepper.
Return the chicken to the pot and pour in the chicken broth and diced tomatoes.
Bring the mixture to a boil, then reduce the heat and simmer for 20–25 minutes, until the chicken is fully cooked.
Remove the chicken, shred it using two forks, and return it to the pot.
Stir in the white beans, olives (if using), and lemon juice.
Simmer for another 5 minutes to heat everything through.
Ladle the chili into bowls. Garnish with fresh parsley and crumbled feta cheese.