Why do you need margarine in baking?

Answer:

At one time it was believed that margarine was healthier than butter, but no more.

More information:

You would only substitute margarine for butter in any circumstances if you had only margarine and absolutely no way of getting out to buy butter.

Margarine won't give the same flavor as butter, whether in Sandwiches, in baking, in making sauces; any food you prepare that requires butter shouldn't be made with margarine. You won't get the same results at all.

Butter is no worse for you than margarine: they're both fats, and in any case the quantity you eat per serve of anything you cook with butter doesn't add up to a huge amount, unless you overdo the eating.

With recipes requiring a large proportion of butter, such as shortbread, the results will be so markedly inferior if you use a butter substitute that you might as well not bother.

If you don't have butter, put off making the recipe until you can buy some, if you possibly can.