Okay, here it is:
John 10:22-30
22 Now it was the Feast of Dedication in Jerusalem, and it was winter. 23 And Jesus walked in the temple, in Solomon's porch. 24 Then the Jews surrounded Him and said to Him, "How long do You keep us in doubt? If You are the Christ, tell us plainly." 25 Jesus answered them, "I told you, and you do not believe. The works that I do in My Father's name, they bear witness of Me. 26 But you do not believe, because you are not of My sheep, as I said to you. 27 My sheep hear My voice, and I know them, and they follow Me.
28 And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand. 29 My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of My Father's hand. 30 I and My Father are one."
NKJV
Okay, I suppose you can interpret this passage a variety of ways. Personally, I believe that it would be interpreted as "if you are in a saved state, then nobody can snatch you out of Jesus's hand other than yourself." So only we can make ourselves unsaved again, and no other person can affect our being saved while we are in a saved state. The verse states that no outside person can snatch saved people from God, however it doesn't state that saved people can't become unsaved again through their own free will and on their own accord.
Where in this selection does it state that "once you are in a saved state, you can never become unsaved?" It doesn't state that.
According to the context of this verse, being saved means "believing that Jesus is the Christ." This is a mental belief. By stating that if someone believes something at one time, then they will believe it for their entire lives is absurd. People can lose faith, or belief in anything, including God.