Party members shall not believe in religion, which is a principle to be unswervingly adhered to, Zhu Weiqun, executive vice minister of the United Front Work Department of the CPC Central Committee, wrote in Qiushi, or 'Seeking Truth' - the biweekly official journal of the Party.
The ban also applies to party members and officials administering the predominantly Buddhist Tibet and Xinjiang, the home of Uyghur Muslims.
Both provinces remained predominantly religious despite over six decades of CPC administration.
"Party organisations will be greatly weakened in the fight against separatism, as hostile forces home and abroad are doing what they can to use religion for their separatist activities in the areas inhabited by ethnic groups," Zhu said.
"It is not accidental that Party committees in Xinjiang and Tibet, where the anti-secession struggle is the most acute, take a clear-cut stand that Party members shall not believe in religion," Zhu said.
Zhu slammed the growing clamour among CPC members participating in religious activities, establishing close contacts with religious figures and some members becoming de facto religious believers.
"Some people, even within the Party, have said the ban of CPC members believing in religion should be lifted. They listed the 'reasons and benefits' for CPC members to believe in religion, and even argue the ban was inconsistent with the Constitution," Zhu said.
"If the Party lifts the ban as some people suggest, it can hardly see the promised benefits and will instead suffer obvious pernicious consequences," state-run Xinhua news agency quoted Zhu as saying in the article.
He said the 90-year-old Party, would suffer "pernicious" consequences if members are allowed to believe in religion.
Zhu's unequivocal assertion apparently was aimed at reassert Party's adherence to Marxism and Leninism despite its decision to deviate from hardline ideological policies of its founder Mao Zedong by steadfastly carrying out economic reforms taking the country on the road to capitalism in the past three decades.
CPC, which attributes its economic reforms as part of its policy of socialism with Chinese characteristics, however, studiously avoids political and religious reforms. There is, however, no ban on people in general practicing religion.
China by and large remained a secular society where Buddhism, which has taken roots ever since it came from India centuries ago, is fast staging a come back after Mao era persecution, while Christianity, both catholic and protestants is also taking strong roots.
Zhu said no religion rule only applied to party members.
It has to be clear-cut that people who are not CPC members have freedom of religious belief and CPC members shall not believe in religion, he said.
He warned against tolerating Party members participating in religious activities.
Those who use their power to fuel religious fanaticism and the excessive construction of religious sites shall be reprimanded, and punished if they refuse to repent and make corrections, he suggested.
The CPC's use of Marxism and all its theories, ideas and actions as a guide is based on the dialectical materialism view of the world, Zhu noted.
The Party will be divided ideologically and theoretically if members are allowed to believe in religion, as it means the coexistence of both idealism and materialism and of both theism and atheism, compromising the guiding role of Marxism.
The Party will be divided in organization if members are allowed to believe in religion, since it means CPC members could be under the leadership of the Party and various religious organizations at the same time.
The CPC would not be able to retain socialist credentials if it disarms itself ideologically and theoretically and degrades from a Marxist party to a non-Marxist one by allowing its members to believe in religion, he said.
He called for more efforts to enhance the Marxist view of religion and atheism education within the Party.