Why is it that some Christians?

Have a desire to put down Islam and Judaism? DO they not realize that they are pretty much putting down the entire old testament (when they harp on Jews) or that we all agree on events up until Jesus (pbuh) comes along? Allright so you don't believe what I believe, fine. BUT don't tell me how my life would be so much better if I believed what you believe. Islam is MY choice. Many christians do not like it when Jehovahs witnesses come to their door, trying to spread their word, well I don't like it some christians decide to take it upon themselves to change my relion or beliefs. THoughts?