Community is a powerful motivator. Just getting involved with other people in an advocacy group can be much more sustaining than acting alone (voting, sending a donation, writing an op ed). An online community like this one or Facebook can be helpful, but I don't think it comes close to gathering in-person with like-minded associates.

Rallies are more transient but can be highly energizing too. I attended the March For Women's Lives in Washington D.C. in April 2004. While over 1,400 co-sponsoring organizations -- and representatives from 57 nations -- participated in the march, seven groups organized it [an example of diverse groups allying on a specific common issue]. Over one million people marched. It inspired me to get involved for years afterwards.

The Women's Marches in January 2016 also helped to crystalize and launch ongoing activism.

I agree the community that is created by a religious organization is one of the main reasons they exist.
I have belonged to several different organizations that were quite successful in getting ideas that I considered moral and right put into legislation. I support black lives matter, several feminist organizations, the ACLU and many others who all stand up for things I believe in.Sometimes I feel like there are too many organizations or tribes within the secular community because I can't support all of them and just want one big umbrella. A problem with the Democratic Party is all of the different tribes within it. In other words, does anyone have any suggestions for an umbrella organization that could bring us all together?

Morality's a concept that's defined
According to the mores of where we grew
And thus by place of birth we are confined
In gauging what is right or wrong to do.