Question: Being a confirmed catholic in 2008, does attending a non-denominational Christian church go against a person’s Catholic beliefs? Also, is receiving communion at a non-denominational church also against the Catholic beliefs?
Attending a non-denominational church is does not go against Catholic beliefs, but receiving communion in that same church is not possible at this time. The key concept here is that of “real but imperfect communion.” In the Decree on Ecumenism (“Unitatis Redintegratio”) of the Second Vatican Council, the Council fathers state: “Moreover, some and even very many of the significant elements and endowments which together go to build up and give life to the Church itself, can exist outside the visible boundaries of the Catholic Church: the written word of God; the life of grace; faith, hope and charity, with the other interior gifts of the Holy Spirit, and visible elements too. All of these, which come from Christ and lead back to Christ, belong by right to the one Church of Christ.” (Paragraph 3) Every Christian is called to work for the unity for which Christ prayed in John 17:21. Going to services at another church and inviting them to come to Mass with you is a nice way of building up mutual understanding and respect. However, because we are not yet in full communion with such churches receiving communion at their celebration and inviting them to receive Eucharist at ours is not possible because it is fundamentally dishonest. For Catholics the reception of communion is the visible sign that full, organic unity exists between myself and those with whom I am worshipping. Where that unity does not exist, reception of communion is not possible. So if your Protestant friends invite you to communion in their church, politely decline and let them know that you are fervently praying with Christ for the day when we will all be able to celebrate the Eucharist together in oneness of belief and practice.
Lastly, choosing to worship in a non-denominational church in place of going to Mass as a Catholic is not permissible for Catholics as well. If we attend a service in a church that is not Catholic as a visitor we are still required to attend Sunday Mass with our Catholic community of faith.