It is probably safe to say that NO church follows the Holy Bible 100%. Just as no man is perfect, no church (comprised of men) is perfect. However, various denominations have varying degrees of deviation from scripture. Some doctrines taught by some churches are blatantly in contrast to God's Word, other deviations are more subtle. Additionally, some deviations can be seen as a matter of interpretation.
The only way to know if a church is following the Bible, is to know the Bible.
2 Timothy 2:15, “Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.”
When we hear something taught that doesn’t sound scriptural, we need to study the scriptures and 'try the spirits'. 1 John 4:1, “Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.”
An example of deviation from God's word might be any church doctrine which claims that one must be a member of an organization in order to be saved. To us the Scriptures clearly teach that the Father draws us individually to Jesus (John 6:44) and that no man can be saved except he come through Jesus (Acts 4:12, 1 Thessalonians 5:9)
Another example would be someone who teaches in a church who is not open to 'being tried' (not open to answer questions about something they taught). Not only does this demonstrate a lack of humility, but could also indicate that error is willfully being taught. We know “God resisteth the proud and giveth grace to the humble,” (1Peter 5:5). “…he who humbles himself shall be exalted,” (Matthew 18:3, 23:12). While lack of humility in a teacher is cause for concern, a bigger concern would be any church policy which deters or forbids open questioning of the teachings or policies.
While most in Christ are doing the best they can to walk in Jesus' footsteps, we are told that some are wolves in sheep's clothing. (Matthew 7:15, Acts 20:29) In order to know the shepherd's voice, we must know and understand God's Word as given in the Holy Bible. If we truly belong to Christ, we will recognize the voices of strangers, know they are not of God, and flee from them. (John 10) May God open our eyes of understanding more and more as we seek to learn His Word and His will for us.