Obama, accompanied by his wife Michelle and daughters Sasha and Malia, took part in Father's Day services near their house at the Apostolic Church of God - a large, predominantly black church in the South Side of Chicago.
This was Obama's first time attending a church service since he announced last month that he had quit Trinity United Church of Christ, which he had attended for 16 years, as he sought to calm concerns about comments by pastors there.
The presumptive Democratic presidential nominee heads back to the campaign trail on Monday with a trip to Michigan, a key state in his November face-off with Republican candidate John McCain.
McCain met on Sunday in Washington with Iraqi Foreign Minister Hoshiyar Zebari. Arizona Senator McCain has vowed to keep American troops in Iraq until the war is won while Obama wants to start bringing them home.
Applause greeted Obama as he walked onto the church stage where a huge choir sat. After shaking hands with the ministers he turned and clapped along with the choir and congregation as a brass band led them in song.
In his 30-minute speech, Obama spoke about the particular struggles of African Americans and noted that more than half of all black children live in single-parent households.
"What I've realised is that life doesn't count for much unless you're willing to do your small part to leave our children - all of our children - a better world," he said.
"Even if it's difficult. Even if the work seems great. Even if we don't get very far in our lifetime. That's our responsibility as fathers and as parents."
