Lutheran and Roman Catholic Church teachings

Both churches do confess what the Bible teaches, that God is triune.  That is why, for example, our church will recognize the Christian baptisms that are performed in the Roman Catholic Church and we will not re-baptize such individuals who wish to join our church.

While there is a common confession in both churches regarding the Triune God, there is an obvious difference in what the churches teach when it comes to the saving work of the Son of God, Jesus Christ.  We believe what the Bible teaches:  that we are saved solely by the merits of Jesus Christ, and our works do not contribute in any way to our salvation (Ephesians 2:8-9; Titus 3:4-7).  The Roman Catholic Church teaches that salvation is a cooperative effort between God and people.  That teaching does not lead to salvation, as the book of Galatians especially explains.  One hopes that members of the Roman Catholic Church reject what their church officially teaches about salvation and trust only in Jesus Christ for their salvation.

I would think that you and your sister could benefit from a more detailed explanation of the doctrinal differences between the Lutheran Church—WELS specifically—and the Roman Catholic Church.  A Lutheran Looks at Catholics provides such a detailed explanation.  It would be a good read for both of you.

Whether or not you read that book, you and your sister will want to search the Scriptures to see how accurately churches present the teachings of the Bible.