The Cross Church exists to glorify God by making disciples who enjoy Jesus together. That last word - "together" - is important. Enjoying Christ is not just something we do alone, but together as a church.
Although the Bible gives no (explicit) commands to become a "member" of a local church, the Bible does (implicitly) assume we will be a member of a local church. In other words, there are simply no categories for living the Christian life outside of commitment to the local church.
In Scripture, every follower of Christ upon being baptized moves into direct relationship with God's church. There are many biblical arguments one could give to establish the necessity of local church membership and its importance for our growth in Christ.
The biggest argument may be that Jesus didn't just die for "you" he died for "us". We matter to Jesus! And if we want to grow as Christians we will do so leaning into one another, not away from one another.
Jesus is the head of the church, the church is his body, and each person is an indispensable member of it. This is why The Cross takes church membership so seriously, agreeing on a 5-fold process for church membership.