You can still sin/fall.
Matthew 13:18-23: “Hear then the parable of the sower. When any one hears the word of the kingdom and does not understand it, the evil one comes and snatches away what is sown in his heart; this is what was sown along the path. As for what was sown on rocky ground, **this is he who hears the word and immediately receives it with joy; yet he has no root in himself, but endures for a while, and when tribulation or persecution arises on account of the word, immediately he falls away. ** As for what was sown among thorns, this is he who hears the word, but the cares of the world and the delight in riches choke the word, and it proves unfruitful. As for what was sown on good soil, this is he who hears the word and understands it; he indeed bears fruit, and yields, in one case a hundredfold, in another sixty, and in another thirty.”
Mark 13:13: and you will be hated by all for my name’s sake. But he who endures to the end will be saved.
2 Peter 2: 20-22: For if, after they have escaped the defilements of the world through the knowledge of our Lord and Savior Jesus Christ, they are again entangled in them and overpowered, the last state has become worse for them than the first. For it would have been better for them never to have known the way of righteousness than after knowing it to turn back from the holy commandment delivered to them. It has happened to them according to the true proverb, The dog turns back to his own vomit, and the sow is washed only to wallow in the mire.