Brazil President Jair Bolsonaro rallies with evangelical supporters in Rio de Janeiro

Thousands turned out in Rio de Janeiro on Saturday in a strong show of support for President Jair Bolsonaro at an event that mixed religion with politics and reflected solid backing by evangelical religious groups for the president in the run-up to elections in October.

Evangelicals have been amongst Bolsonaro's strongest supporters, representing a key voting group as the president seeks to narrow the gap in polls showing him behind rival Luiz Inacio de Silva, Lula, by as much as 18% with less than two months until election day.

Evangelicals filled Rio's Sambadrome to hear their hero declare "God is on our side," in the upcoming vote, even though polls show Bolsonaro lagging Lula 29% to 47%, according to the polling firm Datafolha.

If those numbers hold, Lula could win in the first round of the elections on October 2.

The contrast between the two candidates has never been starker, with conservative Catholic Bolsonaro painting his rival as a "communist and thief," who will lead the country into ruin.

Evangelical Christians, who overwhelmingly support Bolsonaro, dust off old videos of the former president – ​​who declares himself a practicing Catholic – attending an African Umbanda religious rite in which he is blessed.

The image generates a lot of controversy considering that Bolsonaro's wife is a fervent evangelical.

On Saturday she told the audience in Rio that "the hell's door will not prevail against our family and against the Brazilian church and against our Brazil."

In his own campaign, Bolsonaro seeks to convince the voters that he is the greatest defender of freedom of expression and that the media is "at the service of capital."

Bolsonaro promises that he is the standard-bearer in the fight of good against evil, in which the evil that devastates Brazil would be communism, that is, Lula.

The election, however, will be an uphill battle for Bolsonaro. More than half the people surveyed by pollster Datafolha said they wouldn't vote for him under any circumstance, though support has perked up recently amid lower unemployment, reduced gasoline prices and higher welfare spending.

Analysts said they expected da Silva’s lead to fall as the election nears, given that incumbents tend to benefit from the state machine.