In a small bowl, combine the warm buttermilk and yeast. Allow it to sit for about 5 minutes until frothy.
In a large mixing bowl, whisk together the flour, sugar, salt, and baking soda.
In another bowl, beat the softened butter and eggs together until combined. Add the yeast mixture and blend well.
Gradually add the wet ingredients to the dry ingredients, stirring with a wooden spoon or spatula until a soft dough forms.
Knead the dough on a lightly floured surface for about 5-7 minutes until it becomes smooth and elastic.
Place the dough in a greased mixing bowl, cover it with a damp cloth, and let it rise in a warm place for about 1 hour, or until it doubles in size.
Preheat the oven to 350°F (175°C).
After the dough has risen, punch it down and shape it into a loaf. Place it in a greased loaf pan.
Allow the dough to rise again for about 30 minutes.
Bake the bread in the preheated oven for 30 minutes or until golden brown and sounds hollow when tapped on the bottom.
Remove the bread from the oven and let it cool in the pan for about 10 minutes. Then turn it out onto a wire rack to cool completely.