Positionally every believer may be a saint, but there is a practical sainthood that believers are called to.
Romans 1
1 Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God,
2 (Which he had promised afore by his prophets in the holy scriptures,)
3 Concerning his Son Jesus Christ our Lord, which was made of the seed of David according to the flesh;
4 And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead:
5 By whom we have received grace and apostleship, for obedience to the faith among all nations, for his name:
6 Among whom are ye also the called of Jesus Christ:
7 To all that be in Rome, beloved of God, called to be saints: Grace to you and peace from God our Father, and the Lord Jesus Christ.
8 First, I thank my God through Jesus Christ for you all, that your faith is spoken of throughout the whole world.
He is obviously speaking to believers here, if their faith is spoken of throughout the world. So the called to be saints is not talking to unbelievers called to get saved. They are beloved of God, called to be saints. We see the same statement made to the Corinthians...
1 Corinthians 1:2
Unto the church of God which is at Corinth, to them that are sanctified in Christ Jesus, called to be saints, with all that in every place call upon the name of Jesus Christ our Lord, both their's and our's:
The church in Corinth IS sanctified in Christ Jesus, and they are called to be saints. This is not calling them to get saved, they are already saved. They have a higher calling beyond initial salvation, just as we all do.
2 Peter 1
9 But he that lacketh these things is blind, and cannot see afar off, and hath forgotten that he was purged from his old sins.
10 Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
11 For so an entrance shall be ministered unto you abundantly into the everlasting kingdom of our Lord and Saviour Jesus Christ.
We, as believers, have been called to practical sainthood, to reign with Christ as one of His saints. We must make that calling sure, it is not an automatic function of salvation.
Revelation 14:12
Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Jesus.