Why Religious Parties Do Not Contest Elections Unitedly?

When all the politico-religious parties in Pakistan claim to bring Islamic system and laws in the country, why do not they unite under one flag, contest elections with a similar menifesto and run combine election compaign? Heads of all the relious parties are not corrupt as other political leaders are. There are no apparent allegsations of corruptions, fake degrees or tax evadings against them. Majority of the leaders of religious parties have certificates from Religious schools that are considered at par with university degrees. However, Jamaat Islamis has the highlty educated members, intellectuals, writers and honest people. But when they joined alliance MMA ( Mutahida Majlis e Amal) with JUI of Maulana Fazal Rahman and a few others minor religious parties, they were dominated by Maulana Fazal Rahman and they had to follow him and were lagging behind where Maulana harvested the fruits of MMA's tree. Maulana got all the benefits on the cost of MMA. Therefore Jamaat Islami learnt lesson from MMA and did not unite with Maulana. Here comes the point again, why they can not unite for the sake of making Pakistan Welfare Islamic state, if they are sincere with the country. Why do not they throw back their differences and conflicts for a cause. It looks they are playing politics game for their own personal interests not for the nation and the country. When they have no courage and tolerance and can not sacrifice for a big objective, then why they have the slogans of Islamic laws and system in the country. They have factions like JUI (F) JUI (S(). The JUI Samiul Haq group split during the life of Mufti Mahmood RA. No religiou party can get more than 5-6 seasts in the National assembly and no politician is as clever and smart as Maulana is, who gets behefits from every government. The religious parties must gather in an alliance and fight for the same cause. Otherwise the masses are taking them as they take other politicians. Liers, treacherous, corrupt, selfish and power-hungry. Please you people are not like others, you asre religious scolars you must do something productive for the country.