It's amazing how people claim to know God or claim to be in contact with what they know God to be, but yet (for whatever reasons/excuses) won't attend worship services. They may know God or may think they're in contact with Him, but the question is: does God know them? Is He in contact with them?
For those committed Christians/Believers that have had a real encounter with God and are truly connected to Christ, you follow and adhere to the principles of God's Word and align yourself to His Word. And in the Word, it speaks about church attendance. I'm not naïve enough to believe that all churches are perfect or that they don't have problems. Problems live in every single church, synagogue, temple, cathedral because the body is comprised of humans with flaws. And those who do sidestep church more than likely do so because of either a bad experience with a member/ members at the church or simply because they live off their philosophy of not needing to attend in order to have contact or a relationship with God, which makes no sense to me, because if you're in contact with God, you'll keep to His word. Unfortunately, everyone in church is not united, on one accord with God, nor do they desire to edify His Kingdom, nor are they there for worship. But again, if you're committed to God, you attend because you love Him, want to hear His word and learn how to align your life to it and will be too entangled with trying to serve and please Him to notice anything else. If should the time ever come when problems do become a distraction, in keeping with God's Word, you'll pray for unification and peace, simply because you love God and have a love for His people.
As for the underlined part, again, those who are genuinely united in the Body of Christ don't rely on anyone to tell them about their God. Most people know God from their life experiences. Besides, if you truly desire God and value your relationship with Him, you'll chase after Him and diligently seek Him and learn of Him (which comes from largely from individual & collective Bible study and assemble in worship service.)