Originally meaning 'to serve, attend to' (from which we get English 'therapy'), in the NT therapeuo becomes the standard word for miraculous healing. Jesus healed (etherapeuen) every disease and sickness as he traveled Galilee, and he commissioned his disciples to do the same.
The healing ministry is not incidental to Jesus's mission but central to it. Matthew 8-9 records a sequence of healings that demonstrate the arrival of the Kingdom — where God reigns, disease flees. Isaiah 35's vision of the messianic age ('then the eyes of the blind shall be opened, the ears of the deaf unstopped') is being fulfilled. The healings are not just compassionate acts but signs (semeia) pointing to deeper spiritual restoration — the ultimate healing of the broken relationship between humanity and God.