Five hundred years ago the condition of society was not as degraded as it is today. At that time people would show respects to a sannyāsī, and the sannyāsī was rigid in following the rules and regulations of the renounced order of life. Śrī Caitanya Mahāprabhu was not very much in favor of the renounced order of life in this age of Kali, but that was only for the reason that very few sannyāsīs in this age are able to observe the rules and regulations of sannyāsa life. Śrī Caitanya Mahāprabhu decided to accept the order and become an ideal sannyāsī so that the general populace would show Him respect. One is duty-bound to show respect to a sannyāsī, for a sannyāsī is considered to be the master of all varṇas and āśramas.
While He was contemplating accepting the sannyāsa order, it so happened that Keśava Bhāratī, a sannyāsī of the Māyāvādī school and resident of Katwa (in Bengal), visited Navadvīpa and was invited to dine with the Lord. When Keśava Bhāratī came to His house, the Lord asked him to award Him the sannyāsa order of life. This was a matter of formality. The sannyāsa order is to be accepted from another sannyāsī. Although the Lord was independent in all respects, still, to keep up the formalities of the śāstras, He accepted the sannyāsa order from Keśava Bhāratī, although Keśava Bhāratī was not in the Vaiṣṇava-sampradāya (school).
After consulting with Keśava Bhāratī, the Lord left Navadvīpa for Katwa to formally accept the sannyāsa order of life. He was accompanied by Śrīla Nityānanda Prabhu, Candraśekhara Ācārya, and Mukunda Datta. Those three assisted Him in the details of the ceremony. The incident of the Lord's accepting the sannyāsa order is very elaborately described in the Caitanya-bhāgavata by Śrīla Vṛndāvana dāsa Ṭhākura.