Quran is the only reliable source of islam, Even the Sunna is not fully authentic (i wont debate this here, it will take hours to explain the whole thing).
Yes, the most genius concept of Islam is that each and every muslim can have his own brand of Islam. In this regard, it is the most progressive and liberal religion existing.
Some follow this school of believe, some follow the other. Some put their trust in this scholar, some in an another. And even though the following should be consistent (but can change), some even follow in this question this and in another question another scholar.
Then, some mulisms say this is the right kind of islam and others are Heretics, while the others say the opposite. Some will say that abrogation (substitution of earlier by later verses, although both are part of the Quran) of the verses took place, some will deny it. And some say verses are missing, while others say, some verses are invisible (valid, but not written down).
Not to start with the Hadiths or the Sunna, indeed...
And this is, even before it is taken into account that only Allah himself will judge in the end, no matter what stream you followed, it could even have been, in Allah's eyes, the wrong one.
