If you disbelieve, generations before you have also disbelieved. The sole function of the messenger is to deliver (the message).
وَإِن تُكَذِّبوا فَقَد كَذَّبَ أُمَمٌ مِن قَبلِكُم وَما عَلَى الرَّسولِ إِلَّا البَلٰغُ المُبينُ
wa in tukazziboo faqad kazzaba umamum min qablikum wa maa’alar Rasooli illal balaaghul mubeen