Christian belief and the value of the study of the shroud of Turin

Firstly, Christians - or at least those who believe in the biblical Jesus Christ - believe that Jesus is the only way to God and to eternal life.  Many of them also believe in Hell (I don't - I find it a repugnant doctrine and there is much, both biblical and otherwise, against the doctrine)  

It's...complicated.

Traditionally, there are four broad soteriological ("doctrine of salvation") paradigms in the Christian tradition:

Exclusivism - The life, death, and resurrection of Jesus offers the only path toward liberation of humanity from its bondage to sin and death, and this path can only be trod by those who acknowledge Jesus in this life.

Inclusivism - Salvation through Jesus, as above, except it is possible for those who do not adopt Christian convictions. Variations on this idea are the post-mortem offer of salvation or God's condescension to judge persons insofar as they respond to the "light" they receive. Justin Martyr, 2nd century AD, is the earliest clear case of an inclusivist theologian.

Universalism - All will be saved through Jesus, one way or another, eventually. Explicit support as far back as Origen (2nd-3rd centuries), arguably back to St. Paul. 

Pluralism - A more contemporary approach in our more globalized world; supposes that God has laid out many paths of return and the way of faith in Christ is but one of the paths. Precedent can be found at least as far back as Nicholas of Cusa in the Renaissance period.