Postmodernism
Postmodernism does away with many of the things that religious people regard as essential.
For postmodernists every society is in a state of constant change; there are no absolute values, only relative ones; nor are there any absolute truths.
This promotes the value of individual religious impulses, but weakens the strength of 'religions' which claim to deal with truths that are presented from 'outside', and given as objective realities.
In a postmodern world there are no universal religious or ethical laws, everything is shaped by the cultural context of a particular time and place and community.
In a postmodern world individuals work with their religious impulses, by selecting the bits of various spiritualities that 'speak to them' and create their own internal spiritual world. The 'theology of the pub' becomes as valid as that of the priest.
The inevitable conclusion is that religion is an entirely human-made phenomenon.
Precedents
This is not a very new development. In Japan, many people have adopted both Shinto and Buddhist ideas in their religious life for some time. In parts of India, Buddhism co-exists with local tribal religions. Hinduism, too, is able to incorporate many different ideas.
Ways to God
In a world where there is no objectively existing God "out there", and where the elaborate sociological and psychological theories of religion don't seem to ring true, the idea of regarding religion as the totality of religious experiences has some appeal.
Religion in this theory is created, altered, renewed in various formal interactions between human beings.
Images and ideas of God are manufactured in human activity, and used to give specialness ('holiness'?) to particular relationships or policies which are valued by a particular group.
There is no one 'right' or 'wrong' religion - or sanctifying theory. There are as many as there are groups and interactions, and they merge and join, divide and separate over and over again. Some are grouped together under the brand names of major faiths, and they cohere with varying degrees of consistency. Others, although clearly religious in their particular way, would reject any such label.
Some examples
Some of these interactions are labeled 'religious': rites of passage like weddings and funerals, regular worship services, prayer meetings, meditation sessions, retreats.
Some of these are just the rituals of everyday life. These include cooking and cleaning, and working. (Many established religions had that insight a long time ago - although they required the actions to be carried out with a particular attitude of mind to count as religious.)
Yet others are group actions designed to "bring about the Kingdom of God" on earth. These are often initiatives for social change, or charity work, or fighting for individual human rights.
These dramas remove religion from the exclusive narratives of scriptures, or the lifestyle rules of various faith communities, and bring religion into everyday life.
They enable people from different faiths, or none, to work together in religious acts when they engage in social action - they are working to bring about the Kingdom of God on earth, and they don't worry about who God is, or whether God is.