Speaking in Ankara, the will tackle fears among Eurosceptic Tory MPs that a Muslim nation with a population of 72 million people would swamp the EU and result in a new wave of immigration to under Europe's free movement policy.
Referring to Turkey's membership of Nato and its goal of joining the EU, Mr Cameron will say: "My view is clear. I believe it's just wrong to say Turkey can guard the camp but not be allowed to sit inside the tent."
One group which opposes EU entry are "the prejudiced" who wilfully misunderstand Islam, he will claim. "They see no difference between real Islam and the distorted version of the extremists. They think the problem is Islam itself. And they think the values of Islam can just never be compatible with the values of other religions, societies or cultures."
Dismissing these arguments as "plain wrong," he will place the coalition Government at the forefront of an international effort to defeat them.
"Turkey is a secular and democratic state. This is all the more reason to make Turkey feel welcome in Europe," he will say. "I will always argue that the values of real Islam are not incompatible with the values of Europe. That Europe is defined not by religion, but by values. The EU is a secular organisation. And Europe welcomes people of all faiths, or none."
Another group against EU membership are "the protectionists" who view Turkey as an economic threat rather than an opportunity to further prosperity. A third group are "the polarised," who see the history of the world through the prism of a clash of civilisations, and believe Turkey has to choose between East and West.
Turkish politicians have threatened to turn away from the West and "look East" if the EU continues to stall talks on EU entry amid public opposition in countries such as France and Germany. Mr Cameron will say that he is "angry" that Turkey's membership bid has been "frustrated".
He will argue: "Turkey can be a great unifier. Because instead of choosing between East and West, Turkey has chosen both. And it's this opportunity to unite East and West that gives Turkey such an important role with countries in the in helping to deliver improved security for us all."
Mr Cameron, who will sign a new strategic partnership agreement with Recep Tayyip Erdogan, the Turkish Prime Minister, will promise his hosts that he will be their "strongest possible advocate" for EU membership and greater influence at the top table of European diplomacy. "This is something I feel very passionately about. Together, I want us to pave the road from Ankara to Brussels," he will say.
"A European Union without Turkey is not stronger but weaker, not more secure but less, not richer but poorer."
The Prime Minister, who is visiting Turkey en route to India, will meet Turkish businessmen today in the hope that his support for the country's EU aspirations will help to boost trade with Britain.
He will tell Mr Erdogan that Turkey will not have to renounce its past to join the EU club. "I'm not asking you to be a different country, to abandon your values, your tradition or your culture," he will say. "We want you to be Turkey – because it's as Turkey that you can play the unique role I have described on building greater security and greater prosperity for all our citizens." However, he will urge the Turks to pursue aggressively the reforms it is making to pave the way for EU membership.
The Prime Minister will appeal to Turkey not to "give up" on its friendship with Israel, despite the deaths of nine when Israeli troops raided a Turkish cruise ship taking supplies to Gaza in May. "No other country has the same potential to build understanding between Israel and the Arab world," he will say.
He will also appeal for Turkey to take a tougher line against Iran over its nuclear ambitions. Ankara is upset by the West's rejection of a proposed "nuclear fuel swap" proposed by Turkey and Brazil. Mr Cameron will argue that the deal would have allowed Tehran to keep about 50 per cent of its stockpile of low-enriched uranium. "So we need Turkey's help now in making it clear to Iran just how serious we are about engaging fully with the international community," he will say.
What Turkey brings to the table
*Turkish membership of the European Union would bring increased economic prosperity, security and stability on the EU's borders. Its membership is supported strongly by Britain and the US, however it has stalled in the face of opposition from France and Germany.
*Both Britain and America see Turkey as a big player and force for stability in the region. It is a useful conduit between the West and Iran – the Foreign Office points to Turkey as an example of how democracy can flourish in a mainly Muslim country.
*It is the world's 16th, and Europe's sixth, largest economy. It is predicted to become the ninth biggest in the world and second biggest in Europe by 2050.
*The total value of bilateral trade between the UK and Turkey was $9.25bn (£6bn) last year. The UK is the second largest importer of goods from Turkey, after Germany. Around 1 million Britons go on holiday in Turkey every year.