Although the question related only to Christianity and agnosticism/atheism, it's important to realize that those are not the only options that may make sense for and to an ex-JW. I know of an ex-JW Buddhist and an ex-JW Hindu (both Westerners who were attracted to those faiths after leaving the Witnesses), and plenty of ex-JW Pagans - mostly Wiccans, but some who follow other indigenous spiritualities and Neo-Pagan revivalist paths. I have been initiated recently into the Druid path. There are several other Pagans who also post here.
After leaving the Witnesses, I spent the better part of a year being areligious, which is not quite the same thing as becoming agnostic or atheist. It was just my period of trying to shed prior conditioning and taking a much-needed break from pursuit of the spiritual. I did try to pray, and I did think about spiritual things a lot, during this period. I just did not seek outside input.
Later, I began to read books concerning science and the paranormal (a favorite subject for debunking in some quarters, yawn). While this is not necessarily directly related to spirituality, paranormal stuff certainly CAN be realted to spirituality, and often the connection is overt, in that religious "miracles" may be calssifed as paranormal phenomena. Anyway, this interest led me into an interest in shamanism and magick on the one hand, and into what quantum physics implies and suggests about spirituality on the other. I want to make it clear at this point that my interests were never narrow. I did not "zero in on" Paganism at this stage. I studied a variety of topics, on their own terms, that are verboten for Witnesses, including hypnotherapy (with an emphasis on the spiritual side, including past-life and inter-life regression, and healing using suggestion and the power of the mind), meditation and brainwave entrainment using audio signals to induce meditative states (a shortcut that may be particulatly valuable for Westerners), Silva Mind Control, Huna (the traditional Hawaiian system shamanism, philosophy, ethics, and magick), psychological energy therapies based on the orientation meridian system, the human aura, chakras, and the energy bodies, intuitive and shamanic healing, holotropic breathwork, and many other similar and related topics. I began to peruse, and in some cases investigate, systematic techniques for healing and transformation that had a spritiual basis. I am almost certainly alive and hopeful for the future today as a direct result of pursuing these interests. I also think that a study of human spirituality that fails to take such into account is woefully incomplete.
When I was ready, I accepted a friend's invitation to accompany her to religious services, at an interfaith church. I was amazed at the apparently authentic spirit of love and cooperation that existed there between people of varied spiritual backgrounds and paths, and at how much in terms of genuine spirituality such people could share. Granted, the services and rituals of that church would not be for everyone, but to me they were like food for the starving, or water for one who had been stricken by drought for decades (including the time I spent as a Jehovah's Witness). In fact, although I had attended mainline denominational Christina churches previously, I would say that this was my first encounter with genuine spirituality in a group setting.
I also went with the same friend to Spiritualist Church services, and participated in the meetings of a group that discussed books in a private home, exemplifying what a "book study" could be if it were based on the interests and genuine humanity (thoughts, feelings, and spiritual perspectives) of the participants, rather than being yet another venue for dogmatic indoctrination.
Eventually, after all of the exploration summarized above, I learned that my personal beliefs had evolved in a way that brought me into alignment with Neo-Paganism in general, and Druidry specifically. I then contacted a Druid who had founded an interfaith Grove embracing Druids, Wiccans, magickal and Pagan-friendly Christians, and "anyone who walks in the door" with a friendly spirit and openness of mind and heart. I've been happily associated with this group ever since, for about a year and a half. I have completed a course in Bardic concepts and practices, and have been initiated at that level. (The ancient Druids were subdivided into three groups, Bards, Ovates, and Druids, with concentrations of "theory and practice" peculiar to each group. At least some modern self-designated "Druids" recognize and follow this system of specialization today. Druidic studies build upon Ovate studies, which in turn require Barid knowledge and experience.)
It is very important that Christians, Jew, Muslims, and others in this culture become educated about Paganism, at least to the point that certain common misconceptions are vanquished and banished.
Paganism is not a "fluffy" pursuit most appropriate for teenagers who are beginning a personal exploration of their spiritual natures.
Pagans do not worship the Devil. We do not "worship creation rather than the Creator;" rather, we worship the Creator/Creatrix as embodied in Creation.
We do not embrace and promote practices that are morally and ethically abhorrent to the majority, or anti-social in nature. Love, wisdom, justice, power (-with rather than -over, and personal empowerment), honesty, integrity, and other ethical principles are of highest importance to most Pagans.
In general: We are less judgmental than other faiths. We view one's sexual orientation, and sexual activities engaged in by consenting adults, as purely personal matters. We tend to embrace diversity, rather than fear it.
I am glad to have had the opportunity to say this, in response to the original query.
Warm regards and blessings,
Cruithne
