1) The Lost are not free to believe if their heart has been hardened.
2) What does the phrase"mixed with faith in them"in Hebrews 4:2 mean? The idea is simply to place faith in the gospel, and so if you hear, understand and do not trust or fully trust in the gospel, it does not benefit you. This is like someone who is not open or fully open to embracing the Good News. But they were not like Soil #1 of Matthew 13, for they heard the gospel. Similarly, it is like those to hear but do not learn from the Father (John 6:45).
3) Limited Spiritual Ability refers to the correct and accurate biblical doctrine concerning "natural people," non-indwelt people.
4) Natural people cannot understand spiritual solid food, but can understand and learn from spiritual milk, the fundamentals of the gospel.
The Good News provides the opportunity for many but not all to obtain salvation through faith in the truth.
We must not only hear and embrace the gospel, but God alone must credit our faith as righteousness, thus salvation depends on God's grace and not on our works. Total Spiritual Inability is a fiction, peddled by those who deny Luke 13:24.