Science gives us more options, which is not a moral issue at all and only reflects positively on it. It allows us to live longer, remain more functional, and it makes life easier, safer, more comfortable, more efficient, and more interesting.
And your Christian morality, which is based in ancient, received values from people who didn't know where the rain came from or where the sun went at night, is not my humanist morality, which is based in reason applied to empathy and justice. I consider the American Christian position on abortion immoral.
Once again, not a moral issue regarding the science, but rather, its application.
And once again, I see the Christian attitude immoral and worse, its actions persecuting these people even more immoral. But then again, I'm a humanist, and my values come from a sense of empathy and justice, not ancient superstitions.
What you describe - avoiding STDs because they are diseases - is not moral behavior. It's just good hygiene.
And yet again, YOUR moral values are for YOU. They're not mine.
Also, sexual abstinence is not a virtue, and you can still catch a STD such as HIV being monogamous if your partner isn't.
War, along with the other causes of premature death common in biblical days such as high infant mortality, high maternal death during childbirth, and infection, is why we have to contend with ancient, primitive Christian values regarding sex. The ancients needed every fertile womb (except those of nuns, whose babies would have to be supported by the church along with their mothers) to churn out a baby every year, and anything that interfered with that was declared immoral - maidens remaining unmarried and childless, wives refusing sex to their husbands, masturbation, homosexuality, the rhythm method, early withdrawal, and in more modern times, medical abortion and artificial contraception, were all deemed immoral.
Worse, Christians perpetuate these values mindlessly today - a time when we need fewer people on the planet. In the States, they're back to forcing unwanted pregnancies to come to term as if those new people were still needed to prevent the tribe from going extinct or being made slaves as could happen in antiquity following an insufficiently defended invasion, when these rules were of practical value and importance.
Adultery and fornication didn't make that list. They were declared immoral not because of population concerns, but because of paternity and inheritance concerns.