Anyone who tells you that everything will be okay is a liar.
Some things do turn out okay, but your life will be a series of good times, bad times, and hours where you work or go to school, fulfilling your obligations, and those times are dull gray, the get you through to the next stage.
Anyone who tells you that people are inherantly good thinks too highly of themselves, or else they hold tightly to optimism in order to avoid being a defeatest. This is a survival mechanism, and for them it is necessary. People are not good or bad, nothing is inherent. We are a mixed bag, skittles, M&Ms, and those puke flavored jelly beans. You can eat up or opt-out, but that is all we have on the table.
Anyone who is certain of themselves is a wolf, a self-proclaimed oracle of mankind, really they no nothing, and neither do I. We are better off being adaptive, and being comfortable with change and the unpradicatable nature of life. Live chaotically and nothing will surprise you but yourself.
Anyone who preaches God and salvation to you is a fool. But they are worth listening to. Fools love honestly; they only want you to have a life in the heaven they believe in. They mean well, they love you, and they are trying to do something good. Let them try.
Anyone who tells you they love you probably doesn't know you well enough to be lying about it. When you tell others you love them, try to mean it. If you hesitate or have to think about it before the words come out, then don't say it. Let love build and if it's too difficult to love anyone at any point, let it fade, you'll be better off this way.