My thoughts on truth will come later. This first.
<<The bible doesn't count as proof, for it's a myth and myths have the nasty property to be unreliable when used as proof.>>
OK, moot point. This in itself, you can't say. You have no proof that it is a myth and many historians will agree that the Bible is historically accurate. Not only that, true science never once contradicts the Bible. Most schools of thought won't actually, unless the guy who is speaking is atheist. I have yet to come across someone who can prove that the Bible is a myth.
<<Christ was a normal guy from a (for that time) normal family, with more children. He had an idea and wanted to use it to either improve the world, or only to become famous himself, or both.
Was he therefore objective? No, not in the least.
Someone who claims to be the Son of God is either:
a) leading a cult
b) insane
c) the Son of God
From any of these perspectives, he would NOT be objective. Nobody can be objective because we all come from a certain perspective, our own perspective. Be it yours or mine (or even God's if you believe in him), that perspective will keep you from being objective IN THE SENSE that you will be willing to contradict your own set-in-stone ways to keep no bias in your thoughts. So if I'm a police officer, of course I'm going to arrest a guy who broke the law, no matter what his story. That's something I have to do, he broke the law despite his background, way of thinking, etc. What needs to be decided then is how to deal with him in court. That's not my job, that's someone else's biased work (biased because it needs to follow the law and valid or cogent arguments from the prosecution and defence). Perhaps one view is closer to the truth than another.
Now, my thoughts on truth.
It exists objectively because if it doesn't, who are we? Without objective truth, we cannot be defined (whether as living things, races, or whatever) because it will be up in the air from so many different views. There is no final answer. It's like the difference between a theory and a theorem.