Is a multipurpose theme an alternative to modifying or creating a theme from scratch?

In my opinion, multi-purpose themes are the worst thing you can use, especially if you have specific goals in mind. Whatever theme you choose, you can use it without any code changes, and in the same time, if you run into problems with multi-purpose theme and need to make changes to the code, you will need a lot more time to do it then with simpler niche themes.

If you need church theme, there are specialized themes and even theme shops dedicated to church themes. If you find the right theme, you will not need to make any code changes. And, even if you need to do it, the simpler theme is simpler to modify.

My advice: when you have a specific goal in mind, stay away from multipurpose themes. And stay away from any shop claiming that their theme is ‘easiest’ to build a website with.