Sorry, but the parable of the four soils clearly indicates that salvation/faith can be taken away after receiving God's Word into one's heart. In fact, it was both the second the third soil, in which God's word was heard and taken to heart, yet both lost later on.
Matthew 13
20The seed sown on rocky ground is the one who hears the word and receives it at once with joy.
21But he has no root and lasts only for a time. When some tribulation or persecution comes because of the word, he immediately falls away.
22The seed sown among thorns is the one who hears the word, but then worldly anxiety and the lure of riches choke the word and it bears no fruit.
So, from the parable of the 4 soils, it is possible to receive God's Word and later discard it. There is nothing in the parable of the 4 soils that supports OSAS.