As a Unitarian Old Reg may not profess to the Nicene Creed as Unitarians deny the Trinity.
My understanding of the Unitarians is that they are open to all.
From the uua.org website:
Principles
There are seven principles which Unitarian Universalist congregations affirm and promote:
The inherent worth and dignity of every person;
Justice, equity and compassion in human relations;
Acceptance of one another and encouragement to spiritual growth in our congregations;
A free and responsible search for truth and meaning;
The right of conscience and the use of the democratic process within our congregations and in society at large;
The goal of world community with peace, liberty, and justice for all;
Respect for the interdependent web of all existence of which we are a part.
Unitarian Universalism (UU) draws from many sources:
Direct experience of that transcending mystery and wonder, affirmed in all cultures, which moves us to a renewal of the spirit and an openness to the forces which create and uphold life;
Words and deeds of prophetic women and men which challenge us to confront powers and structures of evil with justice, compassion, and the transforming power of love;
Wisdom from the world’s religions which inspires us in our ethical and spiritual life;
Jewish and Christian teachings which call us to respond to God’s love by loving our neighbors as ourselves;
Humanist teachings which counsel us to heed the guidance of reason and the results of science, and warn us against idolatries of the mind and spirit.
Spiritual teachings of earth-centered traditions which celebrate the sacred circle of life and instruct us to live in harmony with the rhythms of nature.
These principles and sources of faith are the backbone of our religious community.
I think that they can believe darn near anything that they want from any source, any religion or anything that they trip over. Reggie might have some more to say on such things.