The Highway Forums General Discussion Open Forum Three marks of a true church

If you were to list the three most important marks of a true church, what would they be? I will withhold my original list until others comment.
The reason I ask this question is that after many years in SBC churches my wife and I became members of a Reformed Baptist church this year. No matter how long one has been a Christian, one must complete a New Members Class before becoming a part of this particular fellowship. During a certain assigned reading portion of this class I came across this bit of information that goes back to one of the confessions and for one of the items it was an eye-opener for me.
Make your list without doing research, please.