1.  Excerpts from John supporting Salvation by Faith Alone:
 

1:12  Yet to all who received him, to those who believed in his name, he gave the right to become children of God--

3:16  "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

3:36  Whoever believes in the Son has eternal life, but whoever rejects the Son will not see life, for God's wrath remains on him."

5:24  "I tell you the truth, whoever hears my word and believes him who sent me has eternal life and will not be condemned; he has crossed over from death to life.

6:28  Then they asked him, "What must we do to do the works God requires?"
29  Jesus answered,"The work of God is this: to believe in the one he has sent."

6:40  For my Father's will is that everyone who looks to the Son and believes in him shall have eternal life, and I will raise him up at the last day."

6:47  I tell you the truth, he who believes has everlasting life.

20:31  But these are written that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.

2.  Excerpts from John supporting Permanent Salvation:

4:13  Jesus answered, "Everyone who drinks this water will be thirsty again,
14  but whoever drinks the water I give him will never thirst. Indeed, the water I give him will become in him a spring of water welling up to eternal life."

8:35  Now a slave has no permanent place in the family, but a son belongs to it forever.
36  So if the Son sets you free, you will be free indeed.

10:9  I am the gate; whoever enters through me will be saved. He will come in and go out, and find pasture.

10:27  My sheep listen to my voice; I know them, and they follow me.
28  I give them eternal life, and they shall never perish; no one can snatch them out of my hand.
29  My Father, who has given them to me, is greater than all; no one can snatch them out of my Father's hand.
30  I and the Father are one."

11:25  Jesus said to her, "I am the resurrection and the life. He who believes in me will live, even though he dies;
26  and whoever lives and believes in me will never die. Do you believe this?"

1 Jn 2:26  I am writing these things to you about those who are trying to lead you astray.
27  As for you, the anointing you received from him remains in you, and you do not need anyone to teach you. But as his anointing teaches you about all things and as that anointing is real, not counterfeit--just as it has taught you, remain in him.