How are verses 22 and 23 of Surat Al-Fath, which state that Muslims will not lose a battle against the disbelievers, to be understood, despite reality contradicting this?

The two noble verses from Surat Al-Fath: ﴿And if those who disbelieved had fought you, they would have turned their backs [in flight]; then they would not find any protector or any helper [This is] the way of Allah which has passed on before. And never will you find in the way of Allah any change﴾ were revealed after the Treaty of Hudaybiyah and the Pledge of Ridwan. They convey glad tidings that the disbelievers of Quraysh would not stand firm against the Prophet, peace and blessings be upon him, and his companions in any battle from that day forward; rather, they would be defeated and flee. This was a victory from Allah to His Prophet, confirmed by the statements of the early Salaf imams and exegetes such as Qatadah and Al-Tabari. This promise was fulfilled, as Quraysh did not stand firm against the Muslims thereafter; instead, people entered the religion of Allah in throngs.

No scholar has ever said that the verse promises victory for believers in "all" their battles, for reality contradicts this, even during the time of the Prophet, peace and blessings be upon him. Rather, the "way of Allah" is that war is a struggle with alternating fortunes, but the ultimate outcome is always for the pious, as Heraclius deduced from this the prophethood of the Messenger, peace and blessings be upon him. The promised victory for believers is Allah's help for them if they support His religion and establish their faith, as Allah Almighty said: ﴿O you who have believed, if you support Allah, He will support you and plant firmly your feet﴾. Victory is not necessarily only material; it can also be through steadfastness in religion and supporting its law. An example of this is the story of the boy of the People of the Ditch (Ashab al-Ukhdud) who supported the truth by his martyrdom.

The way of Allah concerning His prophets and pious servants is that the ultimate outcome will be theirs. The Prophet, peace and blessings be upon him, gave glad tidings to this Ummah of glory, elevation, and empowerment on earth, and that this religion will reach wherever night and day reach, and by it, its people will be honored, and disbelief and its people will be humiliated. He also gave glad tidings to the Muslims of fighting the Jews and overcoming them.

So, Allah promised His believing servants victory in this worldly life and the Hereafter if they uphold the truth of faith and its obligations. He, the Exalted, perfected the religion and made it manifest through proof and clear explanation, and with power and the sword. This manifestation will remain until the Hour is established.