If God loves Christians,why do churches need lightning rods?

God hates churches and trailer-parks.

What we experience here on earth or in the universe in general is not a question whether God loves or not. I think God created the universe to follow a certain law (physics, etc) and let us live in it by leaving us with two tasks, the compulsory (required to live like breathing and eating) and the optional (believe in God, do good deeds or crimes). The later will be on what we will be judged on the most.. How we interfere with the surrounding world is subjected to what is called fate.

one of the (many) reasons the new england area, once the most religious - now the least religious, lost their faith in the 1900s, ...was because of a huge earthquake that happened on an easter morning when the churches were filled with families.

the death toll was huge

christianity in that part of the US was never the same after that.

Because Christians are subject to the laws of nature God created, just like everyone else. You may be shocked to hear this but Christians are even subject to the Law of Gravity, and if they fall out a window they fall to the ground just as a pagan would!

Structural plan established by the city's building code? What lightning rods?

What does buildings/churches have to do with God loving man?

For the same reason you might love your teeth but you still brush them.

For the same reason as synagogues.