Paul's "Letters of Recommendation"
In 2 Corinthians 3, Paul discusses the idea of "letters of recommendation." He is telling the Corinthians that, because of the relationship and ministry that is already known to them about Paul, he should not need any other "letters of recommendation." This has led us to believe that it would have been normal for visiting brothers to carry a letter from his church to verify that he is a person that is in good relationship with the body of Christ and with the Lord. We live in a different age now where people can be known via emails and phone calls. But, the need is still there to have some sort of relationship with a person before they are given the floor and can take time during the meeting.
Our time of breaking bread and edification only happens typically once a week, and time is relatively limited (we aren't together the whole day). We believe it is wise to help brothers and sisters who have never been a part of an open meeting to have someone help them understand the purpose (edification of the whole body) of why we share. This is a time for the Holy Spirit to lead each one however He sees fit. If a guest comes in and doesn't understand the biblical pattern for this open time and the biblical purpose, a brother or sister could come in for the first time and quench the Holy Spirit.
All that said, if we know someone or a person is known by someone we trust, then we take that to be almost like Paul's letter of recommendation he referred to in 2 Corinthians 3. We would be blessed to have such a person share and build during the meeting. We want to make sure that if only 2 or 3 people are to speak, that those sharing understand the seriousness of why and how they ought to speak.
We believe the church functions based on relationships that we have with the Lord and with each other. If a person comes in that no one knows, and we know nothing about where they are in their understanding of scripture and how to be led by the Holy Spirit in their sharing, we would rather get to know them a little first. The basic training time is a perfect opportunity for us to get to know you and you us. Not only will it help you understand about our gatherings, but wonderful foundational truths about walking with Jesus are shared during the study.