Salvation comes through Christ. The Church is the body of Christ on earth, the mystical continuation of the Incarnation. To His body, the Church, Christ entrusted the authority to mediate His grace, His salvation, to the world. Thus all salvation flows from Christ through His Church to mankind. That being said, there are many, while not formal members of the visible Catholic Church, who are imperfectly joined to Her by virtue of their baptism or even baptism of desire.
He said therefore to them again: Peace be to you. As the Father hath sent me, I also send you. When he had said this, he breathed on them; and he said to them: Receive ye the Holy Ghost. Whose sins you shall forgive, they are forgiven them; and whose sins you shall retain, they are retained. (John 20:21-23)
He that heareth you, heareth me; and he that despiseth you, despiseth me; and he that despiseth me, despiseth him that sent me. (Luke 10:16)
*And I say to thee: That thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose upon earth, it shall be loosed also in heaven. *(Matthew 16:18-19)
Amen I say to you, whatsoever you shall bind upon earth, shall be bound also in heaven; and whatsoever you shall loose upon earth, shall be loosed also in heaven. (Matthew 18:18)