Why do we need a guru? We need a Manthra to connect to Krishna. The Manthra should come through disciplic succession if it should have its full effect.  So, we need a bonafied Guru so that we can get Manthra from him!  And, we can not go to Krishna’s Kingdom directly. Here, our Guru stands as a connecting point between us & Krishna, because, he is already close to Krishna.  For example, if you want to meet the Prime Minister, you can not straightaway go to his office & instantly meet him. You need some connecting persons! Someone who is close to P.M or P.M’s Secretary, like that!  He will take you to P.M’s office.  Because, P.M’s office is the protected area.  Similarly, Krishna’s Goloka is also a protected area. Persons with pending bundle of sins, that have not been cleared yet,  can not enter there. First you should wipe your sins off. You can’t do it on your own. A genuine guru can clear your sins, purify you & take you to Krishna. Like, the Security Personnel/ Secret