Dr.Franklin

For real?! -_- ... The Crusaders *massacred* the Christians of the Middle East...

The Crusades were carried by Franks & Brits, who have never had anything to do with the Middle East & had very little contact with Muslims. They can't "take back" what they never had in the first place. 

Are you talking about the Crusades, or joining a crusade?

 Then why do you keep quoting it. Thanks for conceding.

- Then debunk..

How long before their chanting Seig Heil at Trump's rallies?

Abortion isn't murder.

Any specifics?

The three main reasons given for the Crusades were:

1. Rescuing fellow Christians from invasion and persecution
   
2. Conquering or retaking lands in the possession of Muslims
   
3. Fulfilling personal vows to go on a crusade
   

In my opinion, a war is justified only as a last resort for defense of oneself or others or if it is clearly and directly commanded by God (e.g. God speaks directly to a person). (For more on this, see Onward Christian Soldiers? Christian Perspectives on War by Timothy J. Demy.) Therefore, I consider the first reason to be a possible just cause for war. However, the crusaders seemed primarily focused on the second objective, which casts some doubt on the extent to which they were motivated by the first objective.
With the later crusades, the length of time since the initial invasion should be considered as well. If the current inhabitants of a city weren't alive when the invasion occurred and aren't being oppressed, they're not necessarily in need of rescue. Jerusalem was retaken by the Turks in 1187; Frederick II's and Louis IX's crusades occurred forty and sixty years later, respectively.
As for the second reason, there is nothing in the Bible to support the notion that certain lands (e.g. Jerusalem) ought to remain in the hands of Christians or that Christians ought to take control of lands which belong to non-Christians. The Bible teaches that Christians are to love their enemies (in the case of the Crusades, the Europeans viewed the Turks as their enemies) and help them:

Love your enemies and pray for those who persecute you. (Mt 5:44)
If you come across your enemy's ox or donkey wandering off, be sure to take it back to him. If you see the donkey of someone who hates you fallen down under its load, do not leave it there; be sure you help him with it. (Ex 23:4-5)

Land or other property belonging to non-Christians or a non-Christian government should be left in their keeping (Ex 20:15, 17, Mt 22:21). Furthermore, Christians are not to coerce others into faith (1 Pt 3:15-16). When nonbelievers refuse to accept Christianity, Christians are to move on and evangelize others (Mt 10:14), not punish the nonbelievers (Lk 9:51-56).
Concerning vows, Jesus taught that they should be avoided altogether (Mt 5:33-37). The OT warns against making vows (Pr 20:25) and includes several examples of foolish vows having disastrous results (e.g. 1 Sam 14:24-35).
Behavior of the crusaders
Many of the crusaders' actions were in opposition to the principles of the Bible. This doesn't mean the crusaders were not Christians (though some of them may not have been), for even Christians do wrong. It does mean that not all actions of Christians or those who claim to have God's approval are in fact approved by God.
General Biblical guidelines for Christians' treatment of nonbelievers are discussed in the previous section. Below are some specific wrongs committed by the crusaders and the Bible passages which teach us to do otherwise.

Not according to the Quran, despite your wishes for the opposite.

 I don't like quoting the Bible. But I'm sure you're aware of what I'm talking about.

Fetal studies have shown the baby is alive. Quit saying it's a part of the woman's body.

Do you suffer from a severe case of cognitive dissonance?

In your dreams, I'm sure. You wanna debate that?

War, by design, involves killing... The Quran sanctions Just War -in self-defense against aggressors. 

 What do you think about the violent passages in the Bible?