

Anywho, reading through 1st John today and this passage stood out:
4Everyone who makes a practice of sinning also practices lawlessness; sin is lawlessness. 5You know that he appeared to take away sins, and in him there is no sin. 6No one who abides in him keeps on sinning; no one who keeps on sinning has either seen him or known him. 7Little children, let no one deceive you. Whoever practices righteousness is righteous, as he is righteous. 8Whoever makes a practice of sinning is of the devil, for the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the works of the devil. 9No one born of God makes a practice of sinning, for God's seed abides in him, and he cannot keep on sinning because he has been born of God.
1 John 3 - ESV
This passage and especially verse 6 is often pointed to by Clavinists as a proof of the doctrine of "Perseverance of the Saints". They understand John to be saying that if a person continually sins, then they were never saved in the first place. This theory seems quite strong because the phrases "has either seen" and "known Him" are in the perfect tense, indicating a past action (or lackt thereof) with present results.
Any thoughts anyone? How can this be understood from a non-Calvinistic perspective?