Also...with the wheat and the tares, what church is really, actually safe, especially in these Last Days when it seems that entire denominations have lost their way? Ugh!
CE,
There's a difference between doubts and disappointments.
I don't believe you really have any doubts. You are disappointed with the state of Christendom (which is not the same as Bible Christianity). So perhaps this might help.
1. Satan entered into all the local churches while the apostles were on earth, and began to corrupt them from pure, simple Bible Christianity and the true Gospel to a perverted Gospel and perverted practice.
2. Between 400 and 1400 AD, the Roman Catholic and Eastern Orthodox churches dominated Christendom and practised a corrupt form of Christianity where the light of the Gospel had almost disappeared.
3. Between 1400 and 1700 AD, the Reformers and the Reformation restored many of the Bible truths, but did not return entirely to Bible Christianity.
4. Between 1800 and 2000 AD, so-called "Christian" scholars attacked the Bible and every major Bible doctrine, and the mainline denominations embraced theological liberalism. Also, a number of cults came into existence.
5. Today, the majority of churches and denominations have abandoned true Bible Christianity and generally decided to go with a "humanistic" Christianity. Obviously there are exceptions.
The Lord and His apostles had already prophesied that this is exactly what would happen within Christendom before the second coming of Christ.
You, as an individual believer, have (1) the complete written Word of God (and stick to the Authorized Version which has been in use for over 400 years) and (2) the indwelling Holy Spirit. You can also have fellowship with the Father and the Son. If you commit yourself to seriously studying the Word, and ask the Lord to guide you, He will teach you. Essentially you must simply "trust and obey".