Others have given good advice.
Those of us who have done this for a living for a long time got our experience by going out and "doing sound" at all levels (of size and quality) and observing the worthwhile skills that other folks have while - at the same time - sorting out those practices that were counter-productive and should be avoided. Along this journey you gain empathy for the musicians' needs and develop an intuitive sense of the physics involved. This process is (in general) not available to the beginning church sound person, either because they have a full time life already or they will not work in those (secular) circles ..... or both. But the only real way you learn the art-science and hands-on part of live sound mixing and system operation, etc, is by doing it.
For a very solid introduction into the physics of audio and acoustics, nothing comes close to SynAudCon, who have been educating folks like me, Ivan, Mac, Brad, Aaron and the other "knowledgeable geezers" (that participate here and are successful in the field) for decades. After you attend one of their classes you then receive their bi-monthly Tech Topics and can subscribe to their listserv. This is very important because your (our) education needs to continue. They try their best and do a good job at hitting all areas of the US. But the chances are that you will have to travel some distance and the combined cost (the course, travel, hotel) is not low. It is worth every penny, however.
I recently did a church project where the volunteer sound guy (who is also an EE) took it upon himself to attend the SynAudCon seminar for sound system operators. What a huge blessing this was for him, his church and for me.
www.synaudcon.com There are also church expo / trade shows that are presented around the US and they often offer classes. But these gatherings seem to be concentrated "down south" and you have to search for them. The quality of the classes varies quite a bit.
HTH