Yes they have real faith demonstrating it by helping Jesus' brethren the Jews during the tribulation. We saw similar acts by 'righteous Gentiles' hiding and aiding the Jews from the Nazi war machine.
It seem happen not only during tribulation but Jesus say
40 “The King will reply, ‘Truly I tell you, whatever you did for one of the least of these brothers and sisters of mine, you did for me.’
To me Jesus brother is believer it do not say during the tribulation.
Is Jesus brother hungry an sick and need cloth, not all but some Christian is poor, we may never meet Jesus in need, we may never meet Jesus physically how we feed Jesus?
By helping the poor brother and sister not only during tribulation