You can't force them to bake a cake for someone, but you can fine them, throw them in jail, or put them out of business for refusing.
However, I suggest reading the Court's opinions to see what reasons they actually used in their ruling.[1]
Their ruling focused largely on how they felt that the Colorado Civil Rights Commission (CCRC) didn't properly respect the baker's religious beliefs, and that the CCRC has demonstrated inconsistencies with their rulings on other similar cases.
However, I suggest reading the Court's opinions to see what reasons they actually used in their ruling.[1]
Their ruling focused largely on how they felt that the Colorado Civil Rights Commission (CCRC) didn't properly respect the baker's religious beliefs, and that the CCRC has demonstrated inconsistencies with their rulings on other similar cases.
[1]https://www.supremecourt.gov/opinions/17pdf/16-111_j4el.pdf