It's a rather rare glitch, which can easily be fixed by fully restarting your game.
If you don't want to lose your current progress, you can save it normally and by the time you restart your game, it will look like nothing ever happened.
All Crusades, Jihads and other Holy Wars are all started by the religious leaders declaring one, for Jihads this is the Sunni and Shia Caliphs. There is no direct way of starting a Crusade or 'goading' them into a Jihad - instead your best option is to try and gain control of important religious territories, this will eventually lead to a religious war being triggered.
Crusader Kings 2 works by applying religious weight to different territory, the higher the weight the more important it is for that religion and thus the more likely it is to trigger a religious war. In your case you are looking to trigger a 'Jihad' which means you need to target the most important Muslim territories, listed below in descending order of 'weight' I have listed the most important Muslim territories...
- County of Mecca (obviously)
- Duchy of Medina
- County of Medina
- Kingdom of Persia
- Kingdom of Mesopotamia
- Kingdom of Egypt
- Kingdom of Jerusalem
- Duchy of Jerusalem
- County of Byzantion
- County of Jerusalem
There are more territories than just these but they are the most significant and most likely to trigger a Jihad if under threat or are under the occupation / rule of a Christian or non-Muslim leader.
Additionally if any of the following conditions are met with regard to territory then a Jihad will automatically begin...
Caliphate Endures - Year is 1187 AND Caliph exists
Fall of Jerusalem - Jerusalem held by non-Muslim
Fall of Mecca - Mecca held by non-Muslim
Center Collapsing - Baghdad, Damascus or Cairo held by non-Muslim
Africa in Danger - Marrakesh, Tunis or Al Dzajir held by non-Muslim
Besides taking territory and directly confronting the Muslims all you can really do is wait for a Crusade / Jihad to begin by letting the religious leaders declare it on their own. You can of course 'sow dissent', 'assassinate' and generally cause as much disruption as possible to the Caliphs to make sure there as fired up as possible but this is unlikely to do much other than make people who probably hate you, hate you more...
Best Answer
There are two kinds of abdication civil wars.
Imprisonment by another ruler means that you will potentially play with a regency for a pretty long time. Regencies are not much fun to play, because they limit your options and can screw you over in a lot of small and large ways. Writing them all out would be enough material for another answer, so if you want the details I recommend reading the wiki article. Let's just say: You do not want to be in a regency for an extended period of time. So all you can hope for is that you die soon or that your captor gives you a chance to leave prison (suddenly likes you and lets you go, offers you to pay ransom, tortures/mutliates/humiliates you if you have the "Reaper's Due" dlc). But if you are not so "lucky" and your character is rather young and healthy, you might spend several decades in prison while a line of corrupt regents ruins your kingdom.
Assuming a "usual" situation, I would prefer abdication over imprisonment over getting replaced, but depending on the circumstances you might have good reasons to prefer these in a different order.