Yes, Hamas is a deadly organization because they have perpetrated a great deal of terror. They have inflicted a great deal of suffering on innocent women and children. Just because there are even more powerful terrorist groups in the world today doesn't diminish the threats posed by Hamas for the victims that they target.
Hamas is a deadly organization. The group is listed by the United States as a terror organization. They are behind many deadly bombings and openly support violence, particularly against Israel. Their tactics include suicide bombings and rocket attacks against both the citizens and military of Israel. These have been condemned by organizations including Human Watch.
In today's world of chaos, it can be hard to differentiate between groups as their disagreements and differences are often subtle. Sometimes groups love Hamas can fly under the radar when a flamboyant, grotesque group like ISIL grab the attention of world powers and the media. But we must not forget that any group that has killed for its principles is a deadly organization.
Well, they kill people so I would think that would be considered deadly. Unless you are somehow immune to death, in which case they still may be deadly to those around you who are not immune to death. Invite them over for dinner and see how deadly they may or may not be.