Why do Ebionites avoid Christian meetings, and meetings made up of Christians (or other religions)?
Ebionites avoid and have a religious right and duty to not attend any meeting or gathering that is led by a Christian or Christians (or any religions other than Judaism) and attended predominantly by Christians (or members of religions other than Judaism). These may be religious meetings, or public, or employment related particularly if you are a government employee. The governments of most nations reflect the whims of the majority, officially or unofficially. Thus the values and mors of the majority religion is given favor at the expense of the religious rights of minorities, including Jews. To attend such meetings can be construed as support of those majority values, mores, and thus the religion. An Ebionite will not support other religions in any measure, nor will it recognize any authority that rests upon the acknowledgement of another religion, even if it means participating with gathered individuals who hold another religion.