Paul, Silvanus, and Timothy, to the assembly of the Thessalonians in God the Father and the Lord Jesus Christ: Grace to you and peace from God our Father and the Lord Jesus Christ.
The church in God, the church in Jesus Christ. And presently Paul is going to be talking about the power of the Holy Spirit with which the message came to them in much assurance. So again, the Father, the Son, the Spirit in which the church was established.