Leaving "religion" aside (whatever that means to you), there is actually an argument from "natural law". In physics charges of opposite signs attract and likes repel, and in biology there exists male and female to increase genetic diversity and hardiness or resistance to disease in a population. If we were all identical, one deadly infectious disease could have the potential to kill almost all of us. We are more spread apart say than several hundred thousand years ago but air travel reduces those distances. In biology 1 + 1 = 3 or more. Male + female is how the creatures on the planet's face reproduce and produce a future for themselves and that is "good". In superstring theory in physics there are no point particles, only vibrating strings, and everything is connected - this seems like "karma" where they say all sentient beings are connected by strong, invisible threads so you have to be careful with what you are doing.