I've explained earlier the Meccans were the ones initiating confrontation with the Muslims - this may be so, but in a sense it doesn't matter - extremist Meccan polytheists aren't causing trouble today, extremist muslims are.
What also matters is the Quran, like the Bible, has lots of violent verses. Christianity, with the odd exceptions of lunatic cults like the WTS, has largely reformed. Islam is yet to have a meaningful reformation. There is also no united, central body of clerics. The diverse range of Islamic interpretation is a huge issue considering the violent Quranic verses that can be taken literally. Although most muslims are peaceful and have Islamic interpretations fit for the 21st century, others do not.