In the OT, healings which are apparently miraculous are recorded during the Exodus of the Israelites from Egypt (Num. 12: 13) and by Elijah and Elisha (1 Kgs. 17: 22; 2 Kgs. 4: 35) and in the NT by Jesus and by the apostles.
It is evident that Jesus was selective in his healings (John 5: 3 ff.) and that the gospels are selective in recording them. There is an element of symbolism in that Mark records twelve miracles of healing of Jews and one of a Gentile (Mark 7: 29). The latter could be Mark's way of implying that the Church enjoyed Jesus' authorization for its mission to the Gentiles. Some healings are of the ritually unclean or outcasts (Mark 5: 29; Luke 17: 16). The miracles in the synoptic gospels are to be understood as visible indications of the approach of the kingdom of God, (Luke 17: 20–1), and in the gospel of John this theological motif is underlined by the use of the word ‘signs’ for the healings recorded.
Some of the healings in the synoptics are exorcisms (there are none in the gospel of John) and the symptoms would be differently diagnosed by modern medicine, but Jesus' healings were real enough. This is confirmed by the honest recognition that Jewish exorcists had equal success (Matt. 12: 27). The accounts in the gospels were intended to support disciples in their beliefs and are explicitly related to the fulfilment of OT prophecy (Luke 4: 21; 7: 21–2). Exorcisms could also be interpreted sociologically: possession by demons reflected a sense of economic and political oppression, and the expulsion of the demons was seen as liberation (Mark 5: 15–17) but, not being unique (Matt. 12: 27), they cannot be recorded as ‘signs’ in John.