((NOTE:The following may be offensive to some. I know plenty of people from many walks of life, be they Christian or atheist. If I got anything wrong, let me know. These are impossibel/worst case scenarios based off of real life events.  If I get anything wrong, let me know!))

Imagine two timelines, Earth and Resa. 

These two worlds stay on track with each other until the discovery of gunpowder. The people of Resa, the Resans, use this material for fireworks, and strictly that. This leads to a massive flourish in every other field of technology, save for weaponry/ defense, which is stuck in a medieval state.

On Earth, the year is 2028. ISIL has launched attacks in Europe,  and initiated Operation Sampson, their nuclear endgame. 

The night of the attacks, an extremist Christan group called Testament is formed, 300 men strong.

Within a month,  their numbers reach 3,000. A grassroots pro-moderate mercenary group called Horizon is formed.

The same night of the formation of Testament,  four Resans crash-land on Earth.

So the story starts on the night of four Resans' arrival on earth. Each one was encased in a power source called Jilida,  which can give one powers if exposed to it long enough,  which has happened to the four. They have obtained a power that has plenty of room to grow. They have two options: fight for Horizon or Testament.