I'm going to make an assumption about my audience and say that the vast majority of you can probably see. Not that I'm against blind people, of course, but the general norm is for people to be able to see, and even those who are blind typically would prefer sight. Speaking for myself, my eyes actually aren't that great. Without my glasses, I cannot see much more than my arm's length in front of me, a condition that hinders my personal life, especially as a photographer, and a Krav Maga practitioner.
As much as I would love to repair my eyes, I know for a fact I can live without them. If they get worse, if I go blind, or if, God forbid, something horrible happens and they get injured or destroyed, I will not die just from having lost my eyes. They are important, but they are not essential.
My heart is a different kettle of fish. This organ works day in and day out, never resting for a second, to keep me alive. When it finally ceases in this vital operation, hopefully when I am old and grey and asleep in my own bed, I will pass on from this world and meet the God who put me here. My heart is essential, and must be protected at all costs.
The lesson here is obvious: Just because something is non-essential doesn't mean it doesn't matter. It is extremely discouraging, then, when Christians treat the Bible so flippantly as to simply dismiss various doctrines as non-essential.
By grace of God, we do not need to be perfect to be saved. Our righteousness is in Christ, and so He is our perfection. Where we fail, He succeeds on our behalf. Thus, there aren't really too many essential issues. The Trinity is an example of essential issue. Jesus says blasphemy against the Holy Spirit will not be forgiven in this age or the next. We must confess Jesus as Lord to be saved. Obviously, the whole goal of this is to get to the Father, so if you deny the Father is God, what are you even thinking? So the Trinity is an essential issue. You literally cannot be saved if you deny the Trinity.
But on the flip side, there are issues like Creationism. If you make errors on Creationism, it can be indicative that you aren't saved, but it will not actually cause you to not be saved. You can take your error right to the judgement seat of God, and while He certainly won't be pleased by your error, He also won't reject you because of it.
But as a Christian, why would you not seek to please God? You not only know that He is worthy of being pleased, just by His Holy nature, but also, you know how far He went for you. And of course, on top of this, there are many great benefits to following His teachings as closely as possible, both in this life and the next. Thus, I contend, being content with error because it's a non-essential issue is as foolish as gouging out your eyes just because you know it won't kill you.
Of course, it is possible, and is indeed the nature of man, to go too far in the other direction and make non-essential issues essential. I have seen, for example, many Arminians accuse Calvinists of having a different gospel (and vice versa). I'm certainly no fan of Calvinism or Arminianism, so I say this with no personal bias: This is wrong. It is wrong to say Calvinists or Arminians automatically have a false gospel, because they aren't in violation of any essential doctrine. It would be better if their errors were corrected, but Jesus isn't going to look at a Calvinist, say "oh, well, you confess that you are a sinner, you confess that I am Lord, and you believe in your heart God raised me from the dead, but you were a bit too firm in your stance on Limited Atonement, so ironically, my atonement is too limited to cover you."
The Christian faith is simultaneously simple and complex. It is simple enough that you don't have to know much in order to be saved, yet complex enough that it took God 66 books to tell us everything He wants us to know. Much blood has been shed for you to have access to that book, and sadly, many nations still do not have the privilege. There are people who have to hide their Bibles in bee hives so soldiers don't search and confiscate them. But it's not essential, right? It's not actually worth getting shot for... No, my brethren, the whole book is worth being beaten with whips, cast out of synagogues, sold into slavery, even coated in wax and set on fire for the entertainment of Nero. So, while we will never be so great as to succeed in every area, we better make our best effort. Anything less is an insult to the God who shed His blood for us.