In both the United States and Turkey, the two countries I can observe most closely, the strength of conservative religious movements has a lot to do with how the religious are better at organizing care-giving and social solidarity compared to more secular people.
In the US, much care-giving is linked to churches. From pastoral visits to the sick to church members pitching together to help a recently unemployed member, especially if you’re relatively poor or in reduced circumstances, churches are often the best help you can count upon. In the US, churches are our social safety net. Christian volunteerism is our exception to possessive individualism. We do not believe citizens owe anything to each other as fellow citizens, but we help out others within and through our congregations. Even if you want more middle-class versions of care-giving or social solidarity, such as a support system for college students, it will be religious organizations that attempt to meet the need. The largest student organizations on our campuses are church-affiliated. We are ruthless competitors in the secular public realm (which is little but the marketplace) but caring human beings in a religious environment.
Turkey is much the same. The public realm consists of a dog-eat-dog marketplace and its extension in government, which is naturally wholly corrupt. Care takes place in the context of ethnic, regional, but especially religious solidarity. Especially if you’re poor, religious involvement is critical to your chances to get support beyond an extended family network. There is little in the way of unions or other secular organizations that can support mutual aid. And it is no surprise that middle class and upwardly-mobile needs for care and support are also met by religious groups. College students, for example, if involved with religious orders, can count on decent housing, tutoring help, and a supportive social environment. Indeed, there are religious groups that pay special attention to recruiting needy students by caring for their needs. Secular public alternatives, when they exist, are usually starkly inferior. After all, citizens are on their own as citizens, but as believers, they have access to care.
If we care about secularism as a real-life political option—not some abstract legal deliverance of liberal political philosophy—we have to think about how to care for each other without depending on the kind of thick, suffocating social connections modeled on congregations. It used to be that the political left was deeply concerned about just such matters. In these postmodern times, I am not so sure anymore. We may be very liberal, and firmly committed to the separation of church and state. Nonetheless, by and large, we just don’t care.