Why do Christians feel as though they need to save people?

Why does it seem that most Christians (not all) feel as though they need to save people and convert them to Christianity? I have seen this time and time again. Christians imposing on other peoples believes as though just because it was not of their belief that it was not of God or dark-sided. I consider myself a very spiritual person delving into my own soul and spirit to find peace and happiness but of a different approach. What is so different about believing in the essence of life in a different manner? why is that so dark? I am greatly into meditation and bettering oneself to understand more of my life's purpose and to just be an all around 'good person'. why do i sometimes still encounter these so called 'christians' that still beleive that I need to be a part of their religion to be truly saved. how insulting this is and demeaning to ones character! do they realize they are doing more harm then good and even maybe tarnishing their own religion in this dogmatic thought and approach??? I am just a curious person trying to find different views on this spectrum of thought. maybe even some enlightenment as to why this behavior exists within the christian realm of thought. this train of thought is completely evident among most of the Christians I have met. You can see this behavior by watching the episode of Trading Spouses with Marguerite Perrine. I am not at all putting down Christianity in any way and wish not to hear any negative connotations or comments on the subject. This is purely meant for intellectual purposes and those that do not wish to positively remark and debate please not answer at all.The purpose of this question is to just delve into the subject for further understanding of the issue. Is it jjust plainly the black and whire right-wing view or something that has just continued on through a thousand years or more. it not true that Christanity itself has brought upon so many deaths and and macres hundereds of years ago and for what? Ludicris all on account of faith? I think so. Thank-you.