Given the understanding of Muslim world, they prefer to deal this mess in their own ways.
former Afghan Mujahideen, funded by CIA/ISI, was created to resist USSR in late 80's. After that, new group was created - taken leaf from previous concept of covert war group; was already dying until USA invasion to Afghanistan revived that group and that group is getting stronger everyday. No one like outside interference, and that alone is good enough to unite all of them as one.
ISIS is getting fueled as long as USA stays, the moment USA leaves, ISIS will no longer find fuel to operate its continuency on Iraq soil.
ISIS situation will be handled, but in time, not right now. A further action from USA will only put ISIS on stronger map than it already is.
I am sorry, but my thinking is not in congruence with yours. The United States must intervene on behalf of all the people that are being oppressed by ISIS. I respect the Muslim world, and the Islamic faith, but in no ways does that allow an excuse for extremists (such as ISIS) the leverage to persecute religious minorities: such as Yazidi, Christians, Kurds, Shii, Jews, Sufis, Sunnis.
What you are asking is for the whole world to turn a blind eye. And wait for a 'Muslim Army' to liberate the region.
Are not Shii muslims? Are not Sufi muslims? What about the Christians, the Jews -- Al Qitab who are specifically mentioned to be protected even in Q'uran.
Thanks,