Nearly a million American evangelicals have Jewish blood relatives, a new survey has revealed, suggesting the strong ties between the two religious groups are more than just theological.

Two per cent of Americans with evangelical beliefs, around 871,000 adults, are either Jewish by birth or have Jewish grandparents, the study by Nashville-based LifeWay Research found.

On top of that one in three had Jewish friends, the survey found.

It comes after another study by the Washington-based Pew Research Center in 2013 found 1.6 million Americans who were raised Jewish or have Jewish parents now say they are Christian.

The figures suggest that the close ties between the two groups, with evangelical Christians a particularly strong voice of support for the modern state of Israel, go beyond any religious motivations.

'For some evangelicals, the Jewish community is family,' said Scott McConnell, executive director of LifeWay Research.

'Evangelicals say it's important to share their faith with their Jewish friends,' he added, pointing to figures in the research that suggest 86 per cent agree sharing the gospel with Jewish people is important and 35 per cent have prayed for Jewish friends in the last week. 'But most evangelicals find this to be difficult for one reason or another.'

The study, published this week, was based on an online survey carried out from September 20-28 last year.

The in depth questionnaire also examined the complex relationship between Christians and Jews and how Christians think they fit into God's plans. It found just over a quarter (28 per cent) embrace 'supersessionism' or replacement theology – the idea that the Christian church 'has fulfilled or replaced the nation of Israel in God's plan'. A greater percentage – 41 per cent – reject that idea, while 32 per cent are not sure. However younger evangelical believers –those between 18 and 34 – are more likely to say Christians have replaced Jews in God's plan. Thirty-four per cent agree, while 30 per cent disagree. Thirty-six per cent are not sure.

Among evangelicals aged 65 or older 48 per cent disagree with replacement theology, 23 per cent agree and 29 per cent are not sure.

'Many evangelicals believe the gospel will be spread to all people in the world before Jesus returns,' McConnell said. 'But they aren't sure if Jewish people have a special place in God's plan any more – this is especially true of young evangelicals.'