Eternity is not ever-lasting time but the real, unfading, indestructible, and timeless Present, for, as Schroedinger said, the present is the only th… - Ken Wilber

Let me start with a short and simple list. This is not the last word on the topic, but the first word, a simple list of suggestions to get the conversation going. Most of the great wisdom traditions agree that: 1. Spirit, by whatever name, exists.
2. Spirit, although existing "out there", is found "in here", or revealed within to the open heart and mind.
3. Most of us don't realize this Spirit within, however, because we are living in a world of sin, separation, or duality—that is, we are living in a fallen, illusory, or fragmented state.
4. There is a way out of this fallen state (of sin or illusion or disharmony), there is a Path to our liberation.
5. If we follow this Path to its conclusion, the result is a Rebirth or Enlightenment, a direct experience of Spirit within and without, a Supreme Liberation, which
6. marks the end of sin and suffering, and
7. manifests in social action of mercy and compassion on behalf of all sentient beings. Does a list something like that make sense to you? Because if there are these general spiritual patterns in the cosmos, at least wherever human beings appear, then this changes everything. You can be a practicing Christian and still agree with that list; you can be a practicing Neopagan and still agree with that list.

We have, for the first time in history, easy access to all of the world's great religions. Examine the many great traditions—from Christianity to Buddhism, Islam to Taoism, Paganism to Neoplatonism—and you are struck by two items: there are an enormous number of differences between them, and a handful of striking similarities. When you find a few essential items that all, or virtually all, of the world's great religions agree on, you have probably found something incredibly important about the human condition, at least as important as, say, a few things that physicists can manage to agree on (which nowadays, by the way, ain't all that impressive).

The beauty of practice is that it transforms us so that we outgrow our original intentions — and keep going! Our motivations for practicing evolve as we mature.