He who walks with the wise grows wise, but a companion of fools suffers harm (Proverbs 13:20).

There are no real biblical directives concerning small groups or discipleship groups.  Some churches may make it seem like there are, in a well-intended attempt to plug parishioners into their small groups / communities / home groups / life groups / fusion groups / whatever-they-might-be-called... But the truth is that there's no sort of biblical equivalent to, "Thou shalt participate in thine church's small group system."  I've looked.

Even so, the Proverbs regularly make the point that community life is good for the soul.  We need to have other people meaningfully involved in our lives, so we can comfort each other, advise each other, instruct each other, and help one another grow wise.  Like it or not, we are influenced by the people with whom we surround ourselves.  For better or for worse.  For myself, I know that community has made all the difference in my life.  Through community, I was given a fresh vision for what the life of faith could really mean.  Through community, I was challenged and encouraged to overcome life-long patterns of sin and self-destruction.  Through community, I learned how to love God with all my heart, soul, mind, and strength.  Through walking with the wise, I've grown wise (and am still growing wiser).

Yes, there are other aspects of the life of faith which need to be considered, such as personal devotion to God and living on-mission... We ultimately need to balance knowing Jesus, becoming like Jesus, and making Jesus known.  So certainly, I would stop short of telling people that our church's smaller-scale communities are some sort of spiritual requirement.  But there's certainly some wisdom in seeking out community.