Would preaching in a church be advantageous for becoming a lecturer?
Would preaching at a church help you to become a better lecturer? Almost certainly, as would any similar experience. During the later stages of my PhD I worked in a very popular small museum giving tours and answering questions from the public. I always tell my students that it was the best way for me to hone my speaking abilities: I really learned how to catch attentions and to convey information in a stimulating way. Further, answering hundreds of questions every day (some of which were strange to say the least) prepared me to diplomatically deal with whatever questions are tossed at me after lectures, talks, and conference papers. If preaching does similar for you, you'll see benefits. 

Would putting preaching at a church on your CV help you land an academic job? No, except in the rare case of that being directly relevant to your teaching post: e.g. I had a housemate who did a PhD in religion, taught at a missionary training school, and landed a job at a religious affiliated Uni in the religion department...they would benefit from preaching on their CV. Just as my museum experience was considered "not lecturing", preaching would be the same. You're simply not drawing on the same pedagogical focus, nor are you teaching towards markable learning outcomes.

Edit to answer your final question. No, I truly doubt you would face any discrimination for mentioning preaching on your CV. You would, however, face panel members who would fail to see why such information is relevant on an academic CV. I didn't put my museum job on my academic CV when I was an early career researcher because it wasn't related to my academic work and was, thus, tangential.