Islam means “submission to God”. Islam is the belief that there is only One God, whose proper name is Allah, which means “ the God”. Islam is the same message given to all the prophets, from Adam, Noah, Moses, Abraham, Jesus, and finally to the Prophet Muhammad, the last messenger (peace and blessings be upon them). They all brought the same message: worship only God, and stop worshiping human beings and their ideas.
The Prophet Muhammad, peace be upon him welcomed even those people who had previously fought him and killed his loved ones. These people later on were to become the heroes of Islam. So no matter what your background and no matter what you may have done or said to Muslims or others in the past, you should rest assured that you will be welcomed with open arms.