One that permanently falls away was never saved…as in the parable of the sower, the word/seed fell on rocky soil or seed was fruitless with the cares and pleasures of this life choking it out. They did not receive the word in submission to Christ as Lord becoming a disciple and follower of him. Repentance must be in the heart of the individual who hears and believes the gospel and it is all a work of God…repentance and faith.
Luke 8:11-15 KJV 11 Now the parable is this: The seed is the word of God. 12 Those by the way side are they that hear; then cometh the devil, and taketh away the word out of their hearts, lest they should believe and be saved. 13 They on the rock are they, which, when they hear, receive the word with joy; and these have no root, which for a while believe, and in time of temptation fall away. 14 And that which fell among thorns are they, which, when they have heard, go forth, and are choked with cares and riches and pleasures of this life, and bring no fruit to perfection. 15 But that on the good ground are they, which in an honest and good heart, having heard the word, keep it, and bring forth fruit with patience.
Scriptures that affirm this…
1 Corinthians 15:1-2 KJV 1 Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; 2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain.
1 John 2:19 KJV 19 They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.