When someone becomes a disciple of Jesus Christ – when that person is indwelled by the Holy Spirit – he or she immediately becomes a member of the church – no other membership is necessary.
At the same time, all believers who are part of that person’s life become responsible for the growth and maturity of that new believer as soon as they find out that he or she is a new believer – no other membership or covenant is necessary.
Also, that new believer is immediately responsible for the growth and maturity of all believers in his or her life – no other membership is necessary.
We become part of the church – the only church of God – the only church that matters – at the same moment that we become children of God and disciples of Jesus Christ. Any other requirement is man-made.