On a nice-weather Sabbath, hold church service in the park to get the community's attention and invite them to worship. While you are playing music, people might think that it is a concert. Assign designated people to engage those who pause to check out what is happening.
The first step is to choose a location that is central and can accommodate many people. Second, make sure you reserve the space from the appropriate authorities and receive the permission needed to host an event like this. Finally, develop a worship team that plans a simple and engaging worship. Involve your youth in this stage, making them key leaders in all aspects of the service. If this is something you could do regularly, it is a great way to invite people to a non-intimidating service that is not confined by church walls. As a bonus, you can serve food afterward for a community potluck.