I believe that God has an organization on Earth. How else would the preaching work be done in a way that we could tell how the work was going? God is a God of order. (I Corinthians 14:33)
So who is God's organization? I can see only one that really does what Jesus said to do. They have made some statements in the past that are largely misunderstood. Some things were outright wrong (like Charles Russell saying that
he was the faithful and wise servant; Matt.24:45). I think that the statements you quoted above are largely true. A person can understand the Bible and get an idea of who God is and what His purpose for the earth has always been, and that He will end wickedness by means of Christ, but there are things that the Bible doesn't answer, like who is "the faithful and wise servant?" It's just not in there. So we have to look and see how Christ's teachings match up with what the churches are doing.
So, I can say that I think by myself, and I could always see what Jesus says in the Scriptures & how the O.T. prophecys about him, and that God is Jehovah. But I never knew what the true Christian Church was until I met JWs. They are the only church that really honors Jehovah and teaches the truth about Him and His Son Jesus.