If God doesn't want believers to sin, why does He know they will?
God never encourages believers to sin, but being omniscient and Creator, He knows they will. John writes to believers that they sin not, yet the old Adam remains powerful and pops up even though reckoned dead. So God provided an Advocate, Jesus Christ the righteous One, who intercedes when they sin.
Les explains that John is writing to believers, not the unsaved world, when he says, "These things I write unto you that you sin not." God never encourages the believer to sin. But because God is omniscient and Creator, He knows believers are going to sin. Some may sin quicker than others, but all will sin because the old Adam is so powerful; even though believers reckon him dead according to Romans, he still pops up, gets his licks in, and causes sin. Therefore, John says, if any man sin, we have an Advocate with the Father, Jesus Christ the righteous One. Les pictures the scene in heaven: when a believer sins, the Advocate immediately comes to the Father and says the believer is under the blood. He picks it up on our behalf.