The archbishop of Canterbury has called for an end to the Israeli occupation of Palestine after a pilgrimage in which she met Palestinians attacked by settlers and others detained without trial.

Sarah Mullally, the head of the Church of England, and the Anglican archbishop of Jerusalem, Hosam Naoum, issued a joint letter on Thursday urging Anglicans around the world to press politicians “to take all necessary measures to establish a credible path towards ending the occupation”.

“This must lead to a viable two-state solution enabling Israelis and Palestinians to live in peace, dignity and security. Jerusalem’s status should be determined through negotiation as a shared capital,” the letter read.

The pair said they feared for “the long-term future of the indigenous Christian Palestinian presence in the Holy Land that stretches back to the time when our Lord walked this land”. They also said Gaza’s health system was in a state of “catastrophic collapse”.

The letter was published after a five-day pastoral visit in which Mullally spoke of the “immense hardships” and “web of checkpoints” Palestinians’ faced in the West Bank, Gaza and East Jerusalem, and preached that Jesus had lived under foreign occupation.

She also planted an olive tree with the family of Daoud Nassar, Palestinian Christians who have been fighting Israeli attempts to seize their land in the West Bank since 1991 and have faced repeated settler attacks.

Mullally said that “when many Palestinian Christians are leaving, olive trees are a symbol of their deep roots in this land” and that the Nassars were an example of “Christian resistance to injustice”.

Lambeth Palace said the visit had been intended to encourage Palestinian Christians at a time when “communities are being violently forced from their land, and illegal settlements are rapidly expanding across the West Bank”.

Mullally and Naoum wrote in their letter that they had “met families who feel unmoored and traumatised by endless conflict” across Palestine and Israel.

“In Israel, the simultaneous fighting of many conflicts at one time, and the deep-seated aftermath of the horrifying atrocities of 7 October, have created a state of intense sensitivity to potential danger that has transformed society and politics,” they wrote.

“In the West Bank, unchecked settler violence, forced displacement, systemic discrimination and expanding checkpoints have left the Palestinian population impoverished, desperate and powerless to enact change. Annexation is already taking place in all but name.

“Meanwhile, the profound suffering in Gaza continues. The international community must not look away; it bears a moral responsibility to relieve this agony and help rebuild Gaza’s society.”

Mullally said the Middle East conflicts were “symptomatic of a deeper political and spiritual crisis – an abandonment of international law and an increasing recurrence of military force”.

During her visit, she met Layan Nasir, 26, a Palestinian Anglican community worker freed after being jailed by the Israeli military, and the parents of Natalie Abu Dayeh, a Christian student who had been held without charge.

In the Christian West Bank town of Birzeit, Mullally told worshippers at St Peter’s church she would use her role as archbishop to seek “the peace you desire and the freedom you deserve”.

In her sermon she said: “In the Gospel of Matthew, Jesus is speaking to a community living in fear: his own people living in an occupied land and under foreign rule … I can only imagine how these words may sound to you today.”

The Church of England’s annual assembly, the General Synod, will debate a motion to review investment policies in the region next month.

The bishop of Chelmsford, Guli Francis-Dehqani, said the debate would be about “justice and human dignity for everyone”.