Why do Muslims attempt to convert Christians, Jews and Sabians to Islam?

I was reading the Qur'an in English, when I came to verse 62 of Surat Al-Baqara I was really confused with the verse. As the English translation of the verse says - > Verily! Those who believe and those who are Christians, Jews and Sabians who believe in one god and perform good deeds, they will surely be rewarded and they should not fear The above sentence is so clear that those who believe in oneness of god and do good deeds can go to heaven (I am emphasizing its BELIEVE not BELIEVED and its WHO ARE CHRISTIANS.. and not WHO WERE CHRISTIANS...) So why we (Muslims) attempt to convert other religious people to Islam? We can ask them to follow the oneness in God, that's enough for them? *I read in many sites but answers were not convincing.*