Jesus did not die on the cross just so we could live comfortable, well-adjusted lives. His purpose is far deeper: he wants to make us like himself (Christlike) before he takes us to heaven.
Much confusion in the Christian life comes from ignoring the simple truth that God is far more interested in building your character than he is anything else.
But you cannot grow to Christlikeness in isolation. You must be around other people and interact with them. You need to be a part of a church and community.
Why? Because true spiritual maturity is all about learning to love like Jesus, and you can't practice being like Jesus without being in relationship with other people.