Welcome first and foremost, glad to have you onboard. And look forward to hear more from you in the future.
Thank you for being so forthright and vulnerable in your introduction, and I’m glad God places you in a yellow field ripe for harvest at your workplace.
Since you mention “thorn in the flesh”, going to Paul’s writing in Rom 7-8 is super helpful for us to reconcile conflicting thoughts of our awareness of sin, yet we keep falling, and of course the solution that we have in Jesus.
First and foremost, God gave us all the laws, so that we are acutely aware of sin. We know when we sin, like you acknowledged. Rom 7:7 says it was the law that showed us our sin. We would never have known that covet is wrong if the law had not said, "you must not covet. And verse 15 says, we want to do what is right, but we don’t do it. Instead, we do what we don’t want to do. But you know, this awareness of sin is necessary so we also acknowledged the need of redemption, and that answer is in Jesus Christ our Lord (verse 25).
The fact is we are all fallen by nature and will fall to sin one way or another, sooner or later, even when we start thinking we will not fall to sin, is in itself a sin of pride/self-righteousness. But there’s a difference when we knowingly, and some rebelliously, indulge in a habitual sin, which can lead to a hardened heart, and we become unrepentant. Sort of like the insects you mentioned who grew immune to the pesticides.
In regards to your second set of question, I would recommend a book “The Case for a Creator” by Lee Strobel (https://www.amazon.com/Case-Creator-Lee-Strobel/dp/0310242096). I gleaned so much scientific wisdom from there. For evolution, you may want to check out Chapter 3 on Doubts about Darwinism.
I won’t claim expert on this field, but immunity would fall under micro-evolution and not macro-evolution. Most creationist allows micro-evolution and it doesn’t goes against Design. Simply said, immunity is a defense mechanism designed by a Creator.
If you have limited scientific knowledge, it is wiser, instead of arguing on evolution, to grant them evolution, and politely ask them about the origin of universe. Because even if evolution is true, they have to explain the origin of life, and they will go into the pre-biotic soup theory, and granted its also true, they still have to explain eventually the first matter, space, and time, which is the Beginning! Even Crick who founded the DNA and a famous atheist, would rather come up with a fairy tale, that takes more faith than a Creationist, of exported spores from alien, called panspermia theory (which actually only pushes the question of the beginning to somewhere else). They would rather grasp any other, even more absurd theories, so long as it’s not creation.
Usually their best defense is to attack back the creationist, “if you say God created the universe, then who created God?” This is a false dilemma presented to you, in fact, this is why it is only logical that we need a creator who transcends space, matter and time, to create them, otherwise you just go into a loop going nowhere in argument.
Of course, before we go into these type of arguments with friends, it is imperative to make sure you have build an open-minded and respectful friendship with them first. And try to discern if they are going through some personal issues, as it is easier to touch them on those basis, rather than intellectually. As the adage says “They don’t care how much you know, until they know how much you care.”
Hope it helps, and see you around bro.
Blessings in Christ,