"Do not be afraid. Take courage. I am here."
This is how Jesus assured the disciples who thought he was a 'ghost'. The Greek verb "tharseite" means 'take courage'. The whole experience is symbolic as the boat represents the Church, the storm, the persecution. Jesus' words encouraged the persecuted Christians (10:26, 17:7, 25:5). The Greek "ego eimi" (I am) echoes the OT formula of self-disclosure of God. (Ex.3:14, Is.43:10; 51:12). Here Jesus revealed himself as one with divine power to subdue nature and to save others.
In Peter's walking on the sea (v. 28-32), Matthew focuses his attention, not on the crowds but the disciple, especially Peter as the model of both doubt and faith. He also portrays Peter as an example of discipleship: learning to understand though still puzzled and uncertain of a number of things. Jesus' intervention to rescue Peter illustrates the fact that only in Jesus can one be saved.
The passage ended with the healing account at Gennesaret wherein Matthew said that 'all' the sick were healed.
This image is reflected in the first reading e.g. Jer. 18-22, wherein stated "the Lord said, 'I am going to restore the fortunes of the tents of Jacob' and in v. 23, 'the storm of the Lord! Wrath has gone forth, a whirling tempest ¡K in the latter days, you will understand this.'"
Lord Jesus only in You can we be saved or healed.