What is the ruling on a young man jokingly saying: "I will leave the religion of Islam in the future," and is this considered apostasy from Islam, and what is he required to do?

Joking with reprehensible speech is impermissible, and one must repent from it immediately, as Allah the Almighty says: "And if you ask them, they will surely say, 'We were only indulging in idle talk and play.' Say, 'Is it with Allah, His verses, and His Messenger that you were mocking?' Make no excuse; you have disbelieved after your belief." So, whoever speaks disbelief in jest disbelieves by that, even if he did not intend disbelief. Scholars have agreed that whoever resolves to disbelieve in the future, or wavers in it, disbelieves immediately. Apostasy is the severing of Islam by intention, or by an utterance of disbelief, or an action, whether one says it in jest, defiance, or conviction.