I'm not familiar who slice is, but if a jew becomes a Christian, then he's a Christian. The Bible does prophesize that hundreds of thousands of jews will become Christians in the last days.
The Bible supports what you're describing (not sure it's completely-related to the Berk topic, but wanted to point this out ) --
1 Peter 1: 1Peter, an apostle of Jesus Christ, ... To God’s elect, exiles scattered throughout the provinces ...
4: 14If you are insulted because of the name of Christ, you are blessed, for the Spirit of glory and of God rests on you. 15If you suffer, it should not be as a murderer or thief or any other kind of criminal, or even as a meddler. 16However, if you suffer as a Christian, do not be ashamed, but praise God that you bear that name.
Acts 11:26 and the disciples were first called Christians in Antioch