Welcome to Just Answer. I am here to help you resolve your tax and finance concerns. Please feel free to ask anytime you need extra help.
His ministry need not be incorporated but to be recognized as a charitable organization/church it should be registered with the IRS and he should apply for exempt organization recognition. Without that donations are not tax deductible for contributors and it will be considered a business subject to all the taxes that apply to a business.
You should consider this as a full grown entity and plan accordingly. That will enable you to look forward and not get any negative surprises.
If you envision it growing as a church then register it as such and seek IRS recognition as such. If it is to be a business all receipts will be taxable to your son but not all expenses will be able to be used as offsets (deductions) against those receipts. If he is to be paid personally as a speaker those payments will be taxable to him. He will be allowed to deduct expenses to travel to the speaking assignments but not anything beyond those costs. His rent (place to live) and personal food costs will not be deductible. That is why I recommend doing it all the way by the book even at this early stage.
Obtaining IRS recognition as a church is difficult but not impossible. It happens regularly. The forms to be submitted must clearly show that he is not doing this for personal gain but has devoted his efforts to a clearly defined purpose. I do recommend that you seek competent professional assistance with the paperwork so that it gets accepted with minimal time delays. Please remember that, until the IRS recognition is granted, contributors will not be able to claim charity status for their contributions on their tax returns and your son will need to declare these contributions as taxable income. To maximize the use of the contributions in his ministry you need to do this the right way by the law. Otherwise, taxes will reduce their utilization.
I understand what you are saying but am concerned and a little confused as to what happens if a church doesn't actually form but my son is asked to speak at conferences, revivals, etc. because at this point we just don't know what to expect. Does the IRS make distinguishments between charitable organizations and churches?
Obviously I am not familiar with the types of charitable organization sections of the IRS but I definitely understand that my son needs to seek charitable organization recognition so if not a church, what other charitable organization should he seeking?
You can consider social welfare organization as well. The other types do not apply to your son's situation as you have described it.
Obviously there isn't a cut and dry answer because it is not a social welfare organization any more than it is a church.
It would seem that you need local professional assistance at this point. The key is to do it right from the beginning and avoid the problems that can come later from doing otherwise. You may wish to gain some knowledge before seeing someone for assistance so that you go in prepared with all the questions. You can review some of this at www.irs.gov or simply do a web search on charitable organizations.
Please feel free to ask if you need additional help.