I mentioned Romans 11:13-24 as an extremely clear anti-OSAS passage previously. There's an other one from the gospels, if one reads it equally straight. There are several accounts, so I'll try to include the details from all.
The parable of the sower. The seed that falls by the wayside and the seed that falls into good soil isn't that interesting in this context but the other two are.
Luke 8:6 Some fell on rock; and as soon as it sprang up, it withered away because it lacked moisture.
Mark 4:5 Some fell on stony ground, where it did not have much earth; and immediately it sprang up because it had no depth of earth. 6 But when the sun was up it was scorched, and because it had no root it withered away.
Mat 13:5 Some fell on stony places, where they did not have much earth; and they immediately sprang up because they had no depth of earth. 6 But when the sun was up they were scorched, and because they had no root they withered away.
Luke 8:13 But the ones on the rock are those who, when they hear, receive the word with joy; and these have no root, who believe for a while and in time of temptation fall away.
Mark 4:16 These likewise are the ones sown on stony ground who, when they hear the word, immediately receive it with gladness; 17 and they have no root in themselves, and so endure only for a time. Afterward, when tribulation or persecution arises for the word’s sake, immediately they stumble.
Mat 13:20 But he who received the seed on stony places, this is he who hears the word and immediately receives it with joy; 21 yet he has no root in himself, but endures only for a while. For when tribulation or persecution arises because of the word, immediately he stumbles.
Whereas the seed sown by the wayside never springs up but is trampled down and then devoured by birds, this seed that is sown on stony ground does spring up. It has life. It doesn't manage to lay down a root and find moisture so it soon withers and dies.
Matthew and Mark aren't clear about the spiritual nature of the person involved but Luke is clear, the person does believe for a while but because he has no depth in himself and there is no flow of living water, he falls away when temptations, tribulations and persecutions come.
The fact that the seed sprouts life and that the person is said to believe, proves that the person was born again for a while before becoming spiritually dead agin.
Luke 8:7 And some fell among thorns, and the thorns sprang up with it and choked it.
Mark 4:7 And some seed fell among thorns; and the thorns grew up and choked it, and it yielded no crop.
Mat 13:7 And some fell among thorns, and the thorns sprang up and choked them.
Luke 8:14 Now the ones that fell among thorns are those who, when they have heard, go out and are choked with cares, riches, and pleasures of life, and bring no fruit to maturity.
Mark 4:18 Now these are the ones sown among thorns; they are the ones who hear the word, 19 and the cares of this world, the deceitfulness of riches, and the desires for other things entering in choke the word, and it becomes unfruitful.
Mat 13:22 Now he who received seed among the thorns is he who hears the word, and the cares of this world and the deceitfulness of riches choke the word, and he becomes unfruitful.
The thorns choke the plant but that doesn't mean that it dies, it merely doesn't produce a crop. An unfruitful Christian but still a born again believer. Mark and Matthew mention the deceitfulness of riches but Luke says that the person is choked by riches and pleasures of life as such. What does that mean ? It resembles the passage where Paul warns those who get married that they will have trouble in the flesh. Which is often interpreted as getting reasons to be angry etc but it could as well mean getting too entangled with the positive side to it. In the next verses he mentions both marriage and riches :
1 Cor 7:29 But this I say, brethren, the time is short, so that from now on even those who have wives should be as though they had none, 30 those who weep as though they did not weep, those who rejoice as though they did not rejoice, those who buy as though they did not possess, 31 and those who use this world as not misusing it. For the form of this world is passing away.
How many of the four end up in heaven ? The last two, if they don't change scenarios. The one sown among thorns and the one sown in good soil. What happens when the one sown among thorns and is largely unfruitful faces temptation, tribulation, persecution ? He may well have a deep root and may manage to withstand all of that, just as my relative that I mentioned previously seems to be doing successfully even though his wife hates the fact that he is a Christian. But the scenarios aren't set in stone and the choked plant is certainly in a weaker position to endure than the one sown in good soil.
How many of the four are saved initially ? The last three, including the one sown on stony ground. He falls away by ceasing to believe and becoming spiritually dead again. The logic involved in the agricultural picture is clear, just as it is in Romans 11:13-24.