Question:

Isn't it true that a Church of God follows the Bible and that this is the one and only standard?  To this extent isn't it also true that some of God's disciples can come to know him directly through His word, so it would follow that some saved persons may exist outside of the Church of Christ? 

It is true that only those who are members of the church will be saved; it is true because all the saved are in the church.  The church is that to which the Lord adds the saved -- Acts 2:47.  The church of Christ that exists in this century exists now because people have obeyed the Gospel and the Lord has added them to His church.  Acts 2 is very clear concerning this.  It is also true that there are restoration efforts and that it is a continuing process.  Many pioneers in the last century were involved in a restoration movement, Thomas and Alexander Campbell, Barton W. Stone, Racoon John Smith, Benjamin Franklin (the preacher), and many more both renoun and unknown.   For one to be a restorationist he or she must be routinely challenging the present teachings of the church and comparing it with what the practice was in the New Testament.  It's important to realize that Acts deals with missionary efforts and not so much Church organization.  The letters Romans through Titus deal more with how those converts lived, their role in the world and the structure of the local churches with which they were identified.  

John said in III John verse 4, "I have no greater joy than to hear that my children walk in truth."

Jesus said, "Santify them through Your truth,  Your word is truth."  John 17:17

That truth is the only thing that will set us apart as members of the Lord's church -- that is we are set apart by our adherence to it.

It is only by forgiveness of sins that we can approach God.  That forgiveness comes by our "walking in the light" or following truth.  John 1:7-9 says:

"But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin.  8  If we say that we have no sin, we deceive ourselves, and the truth is not in us.  9  If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness."