Can someone have always been a Christian without ever hearing the word of truth?
No. Scripture's sequence is that a person trusts in Christ after hearing the word of truth, so no one can have always been a Christian without ever hearing it. Becoming a Christian is not inherited or automatic; it follows hearing and believing the truth, as the context states, 'after you heard the word of truth.'
Les explains that verse 13 gives the order: 'in whom also you trusted after you heard the word of truth.' He then asks how often someone says, 'I have always been a Christian.' Does that fit? Were you a Christian before you heard the word of truth? Impossible. The context contrasts this with Israel: Israel was not always free. So being a Christian is not something one is born with or has automatically; it comes after hearing the truth and trusting in Christ. The surrounding passage also shows believers are not saved merely as a fire escape from hell, but to be to the praise of His glory, those who first trusted in Christ. It does not say this applies to those who were baptized, joined the church, or did good works.
In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,