The question is often asked, why did the early Church fathers refer to the Church as Catholic. Particularly, the Apostle's Creed which is truly an ecumenical symbol of faith and is dated to about a century after the New Testament was completed. It is important to understand that the term 'Catholic Church' simply refers to the universal Church of believers.

Some people have the mistaken idea that the word catholic belongs to the Roman Church, however, in truth it is simply the form of the Greek word [katholikos] which means "about or of the whole". It's from the two root words [kata] meaning pertaining to, or about, and the word [holos] meaning the whole. i.e., the whole Church or the Universal Church.

Before those grounded in sound Biblical Theology broke away from the Church in protest (thus they were called, protestants) of the Church slipping into unscriptural practices, they were a part of the one whole or universal Church. There was no Roman Catholic Church (denomination as we know it), there was the Universal Church.

The name catholic in our day denotes a denomination, but in the early Church it was simply a title meaning universal and had nothing to do with a denomination in Rome. There were no denominations. Denominations are an invention of man. There was only the universal Church, not a Roman Church and a Protestant Church, but one Universal Church.

In the big picture, this hasn't really changed today. The true Church of God is the Universal (catholic, in Greek) Church, no matter what label man puts upon it by denominational edict. There is one Holy Universal Church, and it's existing all over the world in many denominations. It has nothing to do with what is the Roman Catholic Church today.

Since we don't speak Greek, we could just as easily translate it:

I believe in the Holy Spirit,
The Holy Universal Church,
The communion of saints,

Every educated scholar of course knows this. But because Reformed Churches are steeped in tradition, and have a high regard for their creeds (nothing wrong with that) it is still rendered (usually) the Holy Catholic Church. And really, there is no good reason to change it. So long as we all know the word simply means universal.

The Apostle's Creed

I believe in God, the Father almighty,
Creator of Heaven and Earth.
I believe in Jesus Christ, his only Son, our Lord.
He was conceived by the power of the Holy Spirit
and born of the Virgin Mary.
He suffered under Pontius Pilate,
was crucified, died, and was buried.
He descended to the dead.
On the third day he rose again.
He ascended into Heaven,
and is seated at the right hand of the Father.
He will come again to judge the living and the dead.
I believe in the Holy Spirit,
the holy catholic Church,
the communion of saints,
the forgiveness of sins,
the resurrection of the body,
and the life everlasting.
Amen.

It is not called the Apostles' Creed because it was written or authored by any of the Apostles, it is called this because it is actually an excellent brief synopsis of what they taught. It sets forth the Christian gospel in a concise, though pertinent fashion, with reverential and liturgical high regard.