Does being a Christian necessitate a belief in the supernatural? Consider a person who adheres to the scientific philosophy that the laws of nature are the same in all places and all times, and can be determined through experimentation rather than, for example, by divine revelation.

Can this person who adheres to such a philosophy ever become a Christian? As in a follower of the teachings of Jesus of Nazereth? e.g. be good to your neighbours, turn the other cheek, don't murder, etc.

If not what can you call a person who follows Christian philosophy and morals (as oppose to say Islamic philosophy) but does not believe in the possibility of the supernatural. The teachings may be so ingrained in them that they see these morals as self evident. Even though they don't base their behaviour on a desire to live on in an afterlife.

(As an example, in the Jewish tradition there is no heaven as such, and yet Jews have a strict moral code.)
Yes! It is written, “Then I saw another angel flying in midair, and he had the eternal gospel to proclaim to those who live on the earth—to every nation, tribe, language and people.” (Revelation 14:6, NIV)

That people includes many scientists who believe as you describe. Now Jesus described what becoming a Christian means:


  After John was arrested, Jesus went to Galilee, preaching the good
  news of God:  “The time is fulfilled, and the kingdom of God has come
  near. Repent and believe in the good news!” (Mark 1:14-15, HCSB)


Repenting means to change your mind, to agree with God about certain things that you did not believe before, both to agree that your behavior and morals are imperfect and need to change, as well as form new ideas about God.

Jesus promised his disciples that after he rose from the dead, he would send the Holy Spirit. This happened in the Book of Acts. A prominent emphasis in Acts is the baptism by the Holy Spirit. Just as Jesus told Nicodemus, to become a Christian, you must be born from above, aka born again. That is what the church taught and teaches still. 

Jesus said that every blasphemy will be forgiven - even blasphemy against his name - but not blasphemy against the Holy Spirit. (See Matthew 12:31-32.)

Therefore, the proof of necessary repentance is God’s gift of the Holy Spirit. The Holy Spirit is supernatural. Thus the scientist who does not believe in the supernatural can become a Christian, but in the process, they will as a consequence of God’s activity in their life repent of their unbelief and acknowledge what God has done.

In other words, dry things can become wet if you pour water on them. Unspiritual people can become Spiritual if the Spirit is poured on them. 


  “For you are saved by grace through faith, and this is not from
  yourselves; it is God's gift — not from works, so that no one can
  boast. (Ephesians 2:8-9, HCSB)