If you have the Holy Ghost, and are born again, then you will know that the word of God is to be rightly divided; in the Old Testament, God commanded the Jews to conquer the lands that he promised to Abraham, and that did involve killing and war. However, it is up to the Lord on whom to have mercy on and who not to; as it is written, shall the thing formed say unto him that formed it why have you made me this? I think not. Jesus said himself that he could pray to be delivered from the cross, destroy the world and be set free, but, he chose the beatings for our healing, and death and blood shed for our salvation; we, as mere men, cannot fathom the depth of the mind of God, and it is truly futile to try and do so. As it is now, God is so loving and patient, not wanting any to perish, but that all would come to repentance through Jesus the Lord.