How do we respond to those who accuse Abu Bakr Al-Siddiq (may Allah be pleased with him) of not killing any polytheist, and question his courage?

The courage of Abu Bakr Al-Siddiq, may Allah be pleased with him, is well-established through his biography and his stances with the Prophet, peace and blessings be upon him, and during his caliphate. He was the Prophet's companion in the cave and during the Hijra, and his comrade on the Day of Badr. Allah, may He be exalted, used him to stabilize the Ummah upon the Prophet's death and the apostasy of some Arabs. Courage is not limited to fighting with one's hand, and killing many polytheists is not a criterion for it; for the Prophet, peace and blessings be upon him, who was the bravest of people, killed only one polytheist with his own hand. Among the proofs of Al-Siddiq's courage was his steadfastness upon the Prophet's death, peace and blessings be upon him, when he addressed the people and stabilized them with Allah's words, the Almighty: "Muhammad is not but a messenger. [Other] messengers have passed on before him. So if he was to die or be killed, would you turn back on your heels? And he who turns back on his heels will not harm Allah at all; but Allah will reward the grateful." Al-Qurtubi mentioned that this verse is the clearest evidence of his courage and boldness. Sheikh al-Islam Ibn Taymiyyah mentioned that the courage required of an Imam was not found in anyone after the Messenger, peace and blessings be upon him, more complete than in Abu Bakr, then Umar, and that the jihad of Abu Bakr and Umar was in types of jihad other than physical combat, such as the jihad of proof, explanation, and دعوت [dawah], whereas Khalid ibn al-Walid killed many times more than Ali did.