Preheat your oven to 350°F (175°C) and grease or line a loaf pan with parchment paper.
In a medium bowl, mix the flour, baking soda, salt, and cinnamon.
In a large bowl, mash the ripe bananas until smooth.
Add the softened butter and brown sugar to the bananas, and mix until smooth.
Beat in the eggs one at a time, followed by the vanilla extract.
Gradually add the dry mixture to the wet ingredients, stirring gently until just combined.
Fold in the raisins.
Pour the batter into the prepared loaf pan and smooth the top.
Place the pan in the preheated oven and bake for 60 to 65 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely before slicing.