My life is itself a sin...

I walk at the university and I see people and I dont talk to them. I look at them and I ignore them for what they are doing. I go for work I meet people and I dont let it out. I come home and meet my flat mate and I dont tell him. These people are wrong and they are doing wrong, and most of them donot even know why they are here in this world. Some dont want to know and some know but they dont care. They think life is to enjoy as I met this Christian activist who told me that. We are not here in this world to enjoy the life or are we? Yes we are, when Allah created Adam, He put knowledge in him. He was told to enjoy and eat everything he wants from the heavens, but not to be with the wrongdoers. We in this world are here to enjoy the life what Allah has given us and to enjoy what Allah has created for us. But in the limits as the limits were set by Allah for Adam and to refrain from what Allah has forbidden on us as he forbidden on Adam, and Allah is the All knower. It is in the nature of human to commit sins and to be attracted towards the forbidden, and this life is just a test, as Allah has given us the knowledge of Good and Bad, and indeed those who do good and follow Allah's commands are on the right path to success. And those who commit sins find excuses for their doings and they are blind. It is like a lie after a lie after a lie and then you dont feel that a lie is a lie and you get blinded. It is our duty to convey the message of Allah to our fellow humans, am I not committing sin when I know the person next to me is wrong and I dont tell him? Am I not committing a sin when they tell me we (humans) are our self-Allah and I dont tell them the truth? Am I not committing a sin as they refer to the book they have written themselves to find the answers for their life and I dont show them the words of the Creator?