I believe that the Gospel demands that one repents of sin, is water baptized, and filled with the Holy Ghost (this is a theological process called "conversion" that follows "prevenient grace"/"effectual calling").
However, I believe that the Apostles originally baptized in Jesus' name. The Trinitarian formula came later as a Trinitarian innovation. I believe that down through the ages many have received the baptism of the Holy Ghost. Many of ancient church writings speak of those who fell into a "spiritual ecstasy" during prayer wherein there words were unintelligible, they saw visions, spoke to angels, experienced miracles, etc. I don't think they used the terms "baptism of the Holy Ghost", or "speaking in tongues" as we do today...but it was the very same experience.
God judges the heart. One need not have a theology degree and know the finer points of a theological viewpoint to be saved. All they must know is that God (and in essence salvation) is found in Jesus alone. Therefore I believe many Trinitarians down through the ages have been "saved", and no doubt discovered their theology wasn't correct on every point.
I'm a "restorationist". I believe that the church fell into Catholic apostasy and was experienced a series of "revivals" in the Reformation that brought her back in line with Scripture more and more as reform continued. Ultimately, I believe that the Apostolic movement is the advancement made to get "back to the Bible" that we've seen within the past couple generations. Here's a short break down:
Lutheran Church - AD 1517: Saw - Justification by faith...
Presbyterian Church - Ad 1536: Saw - Communion as a Memorial...
Congregational Church - AD 1580: Saw - Separation of Church and State...
Baptist Church - AD 1609: Saw - Water Baptism by Immersion...
Methodist Church - AD 1739: Saw - Personal Holiness...
Christian Church - AD 1820: Saw - Baptism for Remission of Sins...
Trinitarian Pentecostalism - AD 1900: Saw - Baptism of the Holy Ghost - Evidence: Speaking with Tongues as in Acts chapter 2 on the day of Pentecost...
Apostolic Movement - AD 1914: Saw - The revelation of God in Christ (ONENESS), and the truth of baptism in the Name of Jesus Christ was brought into full focus again.
Today, I believe a there is a more subtle "reformation" taking place wherein people are leaving instituationlized denominations and churches to fellowship in a more biblical manner in smaller bodies known as "house churches" or "simple churches". Slowly, the church is now taking the organic form like that seen in the book of Acts.