Affleck entered rehab on Aug. 22 to receive treatment for alcohol addiction
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Ben Affleck and Jennifer Garner stepped out at church with their children on Sunday after he completed 30 days in rehab.

“He went to church on Sunday with his family,” a source tells PEOPLE. The source adds that Affleck, 46, was smiling during the outing because the 30-day milestone means “he has reason to celebrate.”

Affleck looked casual in a white shirt, jacket and shades. Garner, 46, wore a black shirt and pulled her brunette hair back in a bun. The exes share children Violet, 12, Seraphina, 9, and Samuel, 6.

The source adds that “[Affleck] is continuing treatment from both the center as well as his home.”

“He will be continuing treatment for the foreseeable future. His treatment takes many forms: in patient, outpatient, therapy, classes.”

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Garner and her children
| Credit: Vince Flores/

Affleck entered rehab on Aug. 22 to address his alcohol addiction, PEOPLE previously confirmed. Garner drove him to rehab.

“He is seeking treatment,” a source told PEOPLE at the time. “He knew he needed help and was vocal about it.” The actor was previously in rehab in 2001 and announced in March 2017 that he had completed treatment for alcohol addiction.

After Affleck was spotted at his Malibu treatment facility last week, one month into rehab, an insider told PEOPLE, “He is doing much better but needs to continue receiving care.”

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Affleck and Garner in 2015
| Credit: Splash

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The insider added, “As difficult as it was to have his recent trip to rehab all play out so publicly, it now seems the way it happened was for the best.”

A source close to the Peppermint star recently told PEOPLE that when it comes to talking to her children about their father’s addiction issues, “There are no secrets, and Jen is great at explaining what’s going on in ­age-appropriate ways.”

The source added, “She tells them Ben is sick and needs doctors. What she ultimately cares about is his sobriety and whether she can rely on him to co-parent.”