Short codes are usually 5-6 digits in length. A long code is a 10-digit phone number with a local area code. Check out more info here.
Even though they are longer, long codes are in a format most of us are very familiar with. We feel that long codes are less spammy and more human. For churches, long codes, being unique, give you complete control over who is doing what with your telephone number. Lastly, PastorsLine has solved the issue of sending large numbers of texts (text marketing or blasting) that was one big advantage of short codes.
So, when you have another look, short codes are just left with negatives. They cost more. They are highly associated with spam and they are not unique so you have no idea which other businesses and organizations are also sharing your short code.
Find out more information here.