Our 11th point of 11 doctrinal statements reads: "the necessity of maintaining, according to the Word of God, the purity of the Church in doctrine and life." The key words are: maintaining (which implies Biblical leaders who care, and believing congregants who receive instruction); purity (as defined by Scripture); and doctrine and life (ensuring what we say matches what we do). It aims to promote a healthy, Biblical church which will be vibrant, powerful and effective.
Because we see through a glass darkly, and we know in part, God gave pastors and teachers for the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: till we all come in the unity of the faith, and ° that we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine. Orthodoxy (right doctrine) leads to orthopraxis (right practice). The devil knows this; thus, our adversary disrupts our effective witness with wrong ideas. Faithful church leadership exhorts right doctrine, deriving a form of sound words from Scripture, knowing God's sheep hear His voice, so they will receive it not as the word of men, but as it is in truth, the word of God.
Your purification (also known as sanctification) is God's current program for you. While it's not wrong to say God saved us from hell, the Biblical language is He shall save His people from their sins. What's the difference? One is fire insurance; the other, a life on fire for Christ. Jesus came to purify the sons of Levi, and purge them as gold and silver, that they may offer unto the LORD an offering in righteousness. Our Saviour Jesus Christ gave Himself for us, that He might ° purify unto Himself a peculiar people, zealous of good works. Since a double-minded man is unstable in all his ways, Scripture exhorts us to cleanse your hands, purify your hearts, and to cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God. This is a tall (lifelong!) order, and part of God's approach to sanctifying a people for Himself relies on the constructs of the church body.
When purity is abandoned, we could have them that hold the doctrine of the Nicolaitans, which thing [God] hates; or worse yet, we might suffer a prophetess, to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols. Our Lord is watching.