Only weaker versions of what it actually says use knowing, {such as NIV, GWT, ect.} while stronger versions us KNOWLEDGE OF, and even the BEST KNOWN PARAPHRASE VERSION the KJV, USES:
2 Peter 2:20 (KJV)
20 For if after they have escaped the pollutions of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein, and overcome, the latter end is worse with them than the beginning.
You see that knowing as it is used in weaker Verstions, is not referring to SALVATION, it is referring to HEAD KNOWLEDGE OF. Where as KNOWING HIM personally, and intimately in your HEART which is the HUMAN SPIRIT, IS SALVATION. Why is that so CRITICAL TO UNDERSTAND? Or you go off into another ball park, like you do. REMEMBER THE HUMAN SPIRIT THINKS TOO AFTER IT IS BORN AGAIN.
I really like the way that Young's Literal Translation words it:
2 Peter 2:20 (YLT)
20 for, if having escaped from the pollutions of the world, in the acknowledging of the Lord and Saviour Jesus Christ, and by these again being entangled, they have been overcome, become to them hath the last things worse than the first,
That is not SALVATION, because even the Demons KNOW WHO HE IS and WHAT HE HAS SAID in their heads. BUT THEY DO NOT KNOW HIM IN THEIR HEARTS PERSONALLY. WE who are BORN AGAIN, DO KNOW HIM PERSONALLY, because HE IS IN OUR HEARTS (HUMAN SPIRIT), and the Holy Spirit has Baptized (IMMERSED) us into HIS Spiritual Body.
1 Corinthians 12:13 (HCSB)
13 For we were all baptized by one Spirit into one body—whether Jews or Greeks, whether slaves or free—and we were all made to drink of one Spirit.