Preferably in real life and without religion or alcohol.
I don’t feel that our society is atomized or individualistic, but that’s going to depend on what kind of life you live. Standard advice is to join clubs or volunteer, and after a month or 6 months at any given place, sit down and think about whether it’s helping you achieve the social goals that you want to achieve. If it’s not, walk away.
What have you tried so far?
I decided to volunteer at the local railway museum, which then introduced me to the local model railway group, and now I am part of both and meeting many more people aswell. Both for getting out of the house, and meeting new people, it has been awesome not to mention the fun.
Find an activity you would like to do, preferably with people involved, and put yourself out there. Join a club that pertains to an interest. All good ways definitely.
Local ttrpg store
Get involved with something that requires a community.
Sounds stupid, but there’s plenty of things that require groups of people to be possible. Community sports, political activism, board games and cards, etc. typically have easy to join communities created for the express purporse of doing the one thing.