I was talking about the inspiration of Scripture with a friend. He claimed that the Scriptures had some truth and were inspired by God, but were not infallible because men had to have messed it up in our fallibility. He also said that there was no way God forced men to have written the Bible properly according to His exact instructions because God never takes away our free will. My friend is not a Christian, which makes it hard to find a standard from which to debate this, do you have any suggestions?
Though your friend is not a Christian, he is discussing the Bible and its origins. What he is saying that God is not able to accurately deliver His own message to mankind.
The core is the claim is that since God gave people free will, they cannot be forced to relay a message from God just as He wanted. The story of Balaam contradicts his position. When Balak approached Balaam a second time asking for a curse on the Israelites, Balaam rightly responded: "Though Balak were to give me his house full of silver and gold, I could not go beyond the word of the LORD my God, to do less or more" (Numbers 22:18). When Balaam went anyway with Balak's people, God warned Balaam: "Go with the men, but only the word that I speak to you, that you shall speak" (Numbers 22:35). Balaam tried numerous times to curse the Israelites through inspiration but failed. Thus, this proves that God can and does control the words spoken on His behalf. And yet it did not take away Balaam's free will because before departing Balaam told Balak how to get the Israelites to sin so that God would be angry with them.
Paul stated, "Now we have received, not the spirit of the world, but the Spirit who is from God, that we might know the things that have been freely given to us by God. These things we also speak, not in words which man's wisdom teaches but which the Holy Spirit teaches, comparing spiritual things with spiritual" (I Corinthians 2:12-13). When speaking God's words, it is God who selects the word choice, not man. It isn't part and part because "All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work" (II Timothy 3:16-17). The phrase "inspiration of God" literally means breathed from the mouth of God. The claim of the Bible is that it is God's words. That is why it is claimed, "Sanctify them by Your truth. Your word is truth" (John 17:17).
Your friend says the claims of the Bible to be inspired by God, being the very words of God, are false. Therefore, it is up to him to prove his point; surely he isn't making baseless claims, is he? Why should any accept a person's opinion over a document that has thousands of years of history withstanding criticism?
Since he is claiming that the Bible has some truth, how does he determine which parts are true and which are false without resorting to personal opinion?