Is it necessary to register many brands for each type of product? For example, we are a Christian Brand and we want to sell different types of products.

What category did you file with the USPTO for? You can't just start producing or putting your 'brand' on just anything -- it has to be in the category filed for.

Your TM will cover all your products IF they are covered under the category that you filed the TM for.

You get the TM and get into Brand Registry (they are admitting some of their sites on a 'pending' basis).

Be sure that the TM filing is covering the category of items though.

If you stray outside the lines NO ONE will protect you.

For example, your TM is for perfume/fragrances and you suddenly want to "brand" toilet paper you may flush your whole TM.....................

You REALLY need to go to the USPTO site and study what they have for requirements.

I filed in two categories for my items.

From the USPTO website --

Trademark classes are a way for us to organize the goods or services used in applications, assess fees, and aid in searching our database of registered and pending trademarks. All goods and services are “classified” or organized into broad categories of goods or services, as determined by international agreement. Each category of goods or services is assigned a number from 1 to 45, also known as an international class. There are many items listed in each class; however, goods and services are never in the same class.

Although TEAS Plus requires you to pay all of your filing fees upfront, the form automatically selects the correct classification of your identified goods or services. Your application filing fee is based on the total number of international classes in your application. If you can’t find an ID Manual entry appropriate for your goods or services, don’t use the TEAS Plus form; use the TEAS Standard form instead.

For example, you might have a clothing line of golf shirts, dress shirts, and t-shirts. These shirts all fall under the same international class, so your TEAS Plus filing fee would be $250 for the one class. However, if you also provide custom t-shirt printing services, you would have goods and services in two different international classes. In that case, your TEAS Plus filing fee would be $500 ($250 plus $250).