The Church is designed by God to be a blessing to us. We are supposed to be in relationships with other believers, using our spiritual gifts to uphold the body.
Not everyone in a church is believer. Not every Christian treats every other Christian as God would have them--Christians are sinners. Nevertheless, imperfect as we are, God still wants us to be in fellowship with each other. In fact, He commands it (see Hebrews 10:24-25). I know experientially that it's nearly impossible to live a godly life in a vacuum (except maybe if you're in solitary confinement for your faith... God can give those people a special strength despite their separation from the body).
God gave us one another commands (search for "one another" in the New Testament) and we can't obey these commands if we aren't in fellowship with other believers. Being in loving relationships are what God designed to make us all grow towards spiritual maturity, to give us joy, and to testify to the world that our God is alive and powerful, because of our love for each other (see John 17).
Are you reading 1 John? Is that where your question comes from? Let God show you if you are in the faith. I cannot answer that question, if that's what you're concerned about.
God bless.