Here at Pioneer Congregational UCC we tend to be on the progressive side of Christianity. Our covenant among our members states that we are each responsible for our own spiritual journey. So the question about false religions may seem rather odd. However we can say that there is more than one way to express our experience of God without saying every claimed religious experience is valid.
Yes, there are false religions. How can we identify them? I would advise that the first two identifiers have to do with connection and benefit.
I see false religions as spiritual beliefs and practices that cut off the individual from life. In my Trinitarian belief system, for instance, I am connected to all that exists through God as Creator, I am connected to other human beings through God as Holy Spirit and I am integrated in my physical, mental and spiritual aspects through God as the Divine Offspring. As long as a religion fosters any of these connections, it is doing at least part of what religion should do for us.
Some religions, however, tend to disconnect people from nature by being too human-centric, or from other humans by being radically exclusive and even tear people apart within their own psyche through manipulative guilt, extreme dietary demands or teaching self-loathing.
The second identifier is benefit. I would not call something a religion if it is bent on destruction of others or the environment. A question I ask about a group is “If everyone acted as the followers of this religion are supposed to do, would the world be a better or worse place?” Obviously there are some claiming the name of a religion that are not following a true religion because they advocate hate and violence and destruction.
There are other things that may be considered when trying to evaluate a religion. I have only offered two here. If I would be true to my own faith then I would evaluate negatively only when a religion is hurtful to its adherents or to others.