What does it mean to worship today? Worship is to submit yourself to God. Meeting on Sunday is not necessarily worship, but to not meet is to not submit to God. People whose only offering to God is to meet once on Sunday are not really worshiping.
The Bible teaches that Christians should be members of a local church. Christians commit to contribute to a group of local Christians. Being committed to a local group keeps Christians from falling away. Being a member of a local church provides opportunities to serve God and others.