In the end only the Apostles had the TRUE faith..
As a result of this, many [of] his disciples returned to their former way of life and no longer accompanied him. John 6:66
Right. The Sermon was to the disciples and to all those following in their faith, the one holy, catholic and apostolic Church. At the time of the Sermon, the only ones to be taught were the disciples (μαθητης), a learner, trainee, student.