If I were omniscient I would know exactly what steps to take to make this the best of all possible worlds, with the greatest possible degree of happiness and well-being for all sentient life.
If I were omnibenevolent that’s what I’d do, but you didn’t specify that.
I hope you get the job.
Knowing me, I would plan a lot of wonderful things to help mankind improve, but then just procrastinate and never get anything done because I’m too busy watching future seasons of Game of Thrones.
In case you hadn’t noticed, humanity has been gradually becoming morally better since the dawn of time. If you’re immortal, there’s no need to apply a band-aid fix when a more long-term solution is available and preferable. And helping humanity become a better race would be my goal.
But I might have a little fun too, like having airliners accidentally dump loads of bacon over Mecca and Jerusalem.
I couldn’t live with myself if I didn’t do these things immediately:
Make sexual violence physically impossible – anytime someone is about to commit a rape or sexual assault, they come down with crippling nausea that doesn’t go away for an hour. Same goes for non-consensual sadistic acts (i.e. harming someone against their will to gain pleasure from it).
Eliminate every virus/bacteria/other infecting agent/particle of the human STD varieties inside every human, mosquito, or other transmission source outside of research laboratories.
Alter the human reproductive system such that women (and men too) are only fertile when they want to be. No babies happen unless both parties want it to happen.
All people currently enslaved against their will (doesn’t include accurately convicted prisoners) have an easy and safe escape route offered to them in a way that appears to be by chance.
Those are the only immediate drastic actions I can think of – a lot of other things I’d want to accomplish (cure other diseases, prevent wars, solve hunger and poverty, etc.) would go slowly with a lot of experimental steps, unless I can use my omniscience to instantly know a way towards a good long-term outcome without negative consequences.
Kill them all, and let myself sort them out.
Regards,
Shodan
I’d grow a bunch of extra arms, kind of like the hindu deities, only way cooler.
Randall: We made trees and shrubs. We helped make all this.
Kevin: Whew! That’s not bad.
Randall: Yeah. But did we get a thimble full of credit for it? No! All we got was the sack. Just for creating the Pink Bunkadoo.
Kevin: Pink Bunkadoo?
Randall: Yeah. Beautiful trees that was. Og designed it. 600 feet high, bright red, and smelled terrible.
I’d probably be “quietly” culling the Human race of serial killers, violent gang members and dangerous politicians.
But of course, that’d be millions and millions of people, and them suddenly dying in frightening ways would attract attention…
Switching #2 and #3 will make your job go a whole lot smoother.
That was my solution, although handled differently. I would simply slow the birth rate down for humanity until the population dropped to about 2-3 billion, then stabilize at that point. We valued life more when there were fewer of us.
As far as the believers thing, I think that I would make a big, flashy entrance of some kind that would settle the question between the believer and the non-believers once and for all. 
I’d probably just use it to get laid so I’m not a good choice.
I was thinking about this thread last night. Look at me, contemplating!
One of the dreams I still remember from my childhood was along this line of chatting with God. Basically God has a home here on Earth but not just anyone could get to it because it’s a mystical place that both exists and doesn’t exist at the same time. If one truly wanted or needed to talk to God they would have to go outside and start walking in any direction. And keep on walking until in your heart of hearts you truly wanted to talk to God and for a good reason. Then you would turn a corner or round a hill and there would be Gods house and you go up and knock on the day and God opens it and welcomes you inside and you and God get to chat.
So I would do that.
This is along the lines of my Second thing I would do but I couldn’t come up with what I really meant with the words that were coming to me. The closest thing was that I would end Tribalism.
I would take away that thing in our brains that make us want to group up and have the “Us vs. Them” mentality in a bad way. Sports rivalries and the such would be left alone, nothing wrong with some friendly competition.
I would take away the fear of “The Other” or “The Stranger” or the “They are not like me.” thing we have. I would flip that and make humans want to embrace those that are different than them. I would take away the thing that makes us want to be superior to some other type of human in a bad way.
I’m still not really articulating it well but now that I’ve written that out I guess I’d make everyone hippies.
Also I’d get rid of disease and human body stupidness like cancer and alzheiners.
2edgy4me
I’d make group-tripping on a psychedelic (preferrably LSD) mandatory. You’d have to do it at least twice in case the first time was merely disorienting and unpleasant.
Health concernswould exempt you from the above.
The very first thing is to pause and use that shiny new omniscience to figure out the best way to make thing better for people.
It’s not a particularly exciting answer, but… look, I’m pretty sure that if I knew everything, I’d have better ideas about how to accomplish the general goal of ‘make stuff better for people’ than I have now.
I’m not.
First, I want the raw code and all documentation on my desk, now.
OK, give me a couple hundred testuniverses to do beta testing on my modifications.
** rewrites some param strings on adversarial, communication, self-identification subroutines **
Gather a Harem of Comely Mortal Wenches, sire some Demigods & Demigoddesses (if Zeus did, so can I), & farm the work out to the kids.
Learn to delegate.