My organisation, founded by Catholic sisters 40 years ago, lobbies the US Congress for economic justice with a strongly progressive faith voice. This year, motivated by a disturbing proposal for a new national budget, we decided to try something new for us – a 2,700-mile bus tour through nine states that would connect us directly with people who would suffer if the budget were approved.

Catholic sisters work daily with people who live at the economic margins. We planned to stand with our sisters and the people they serve, to hear their stories, and to bring their voices back to Washington. We felt we must do this as our response to calls of the gospel and Catholic social teaching to actively challenge injustice wherever we find it.

The budget proposal we opposed was authored by House of Representatives budget chairman Paul Ryan. The so-called "Ryan budget" would slash funding for programmes that serve people in need while giving bigger tax breaks to the wealthy. He had the backing of fellow Republicans, who hold the majority in the House. His budget was also endorsed by presidential candidate Mitt Romney, who in August named Ryan as his vice-presidential running mate. For two years, we had lobbied Congress to oppose such budget cuts, and we also encouraged thousands of our members to contact their elected officials to voice their opposition. It was time to go out on the road to amplify our collective voices.

Particularly appalling to us as Catholic sisters, Ryan announced that the values in his budget proposal reflected those of his Catholic faith. This is emphatically not true, and the US Conference of Catholic Bishops wrote a series of letters stating that programmes that help people in poverty must be protected.

On June 17, we "nuns on the bus" began our journey in Iowa. We met with people at the economic margins and those who served them, and also visited congressional district offices to talk about how the Ryan budget would harm our nation. What astonished us were the crowds of people who met us throughout our trip. Thousands of people who clearly hungered for a stronger church voice in behalf of social justice – and a US Congress that would move past partisan bickering to a genuine concern for those in need.

We will never forget the crowds and congressional visits, but our visits with the people left the deepest, most lasting impressions.

In Iowa, we listened as Tia talked about how her stay at Maria House had enabled her to complete high school so her family could move into their own apartment. There are those who would cut education funding even though we know that education is key to lifting people out of poverty and helping them become self-sufficient.

In Ohio, we met Jini, who had just attended her sister's funeral. Margaret died because she lost her health insurance when she lost her job. When she developed cancer she had no access to diagnosis or treatment. When fully implemented, President Obama's Affordable Care Act will cover people like Margaret and provide access to healthcare for millions more. Congressional Republicans have tried repeatedly to repeal what they call "Obamacare" and to eliminate funding for its implementation. That is wrong.

At a Virginia farm, we met a little boy who walked with one of our sisters into a blackberry patch, where he presented her with a sweet berry. As she wrote afterwards: "Amazingly, the youngster did not take the first taste of the fruit of his labour. Nor did he try to fill his own belly or pockets in order to save some for a later date. No, Eden was generous and he trusted that there would be enough for all of us."

During our journey, I realised that the Ryan budget has at its heart a lie. Unlike little Eden, who knows the truth, the budget proposal says that our nation is rooted in individualism, selfishness and fear. We are – and must be – a compassionate people. As I said recently to the Democratic National Convention, "I AM my sister's keeper. I AM my brother's keeper." My faith and love of this country tell me this is the truth. This truth also reflects the best of our constitution. I trust that future faith statements like that of "nuns on the bus" will convince all our elected officials as well.