There is only ONE FAITH!
[Ephesians 4:5-6] One Lord, one Faith, one Baptism; one God and Father of all... The body is not disjoined from the Spirit, for then would it not be a body.
So, the real Spiritual Church of the Redeemer is 'one Body.' All the members of that Church partake of the same grace, adhere to the same rule of faith, are washed in the same Blood, are filled with the same hopes, and shall dwell at length in the same blessed inheritance.
I think it is very clear that this 'body' with Jesus as the Head, is the 'one' you should belong to. Everything outside this body is false.