How can the existence of angels and the Noble Messenger Muhammad (peace be upon him) be proven to some secularists?

The existence of the Messenger Muhammad, may Allah bless him and grant him peace, does not require proof. As for the truthfulness of his message, there are proofs, among them: his good conduct before prophethood, the miracles supporting him such as the Quran, his informing about unseen matters that came true, and his victory over his enemies and his conquests. The affirmation of the truthfulness of his message is sufficient to prove the existence of the angels he spoke about, and the denial of atheists does not change the reality of anything.