Question: Could you please explain this Mark 9:24 where the father of the sick child asks Jesus to "help my unbelief"? Also if I were to buy a Bible for a non-believer friend, what version should I get him so it would be easy to read for him?
Response: Mark 9:24 goes back to the issue of faith as an important basis for the miracles which our Lord performed. Remember that in His home town, He "did not do many miracles there because of their unbelief" (Matt.13:58). Mark actually says that He "was not able to do any miracle there except to lay His hands on a few sick and heal them" and that "He marveled at their unbelief" (Mk.6:4-6). Now we know of a certainty that our Lord is God and that God has the power to do anything, so that Jesus "lack of ability" to do miracles in His hometown is on account of the unworthiness of the potential recipients of these miracles, and therefore is due to God's self-imposed policy of restraint in cases of disbelief, and not to any lack of inherent ability. Similarly, Christ could have turned the stones into bread at the devil's behest, but He did not because it would have been a violation of the testing which He had been led by the Spirit to endure (Matt.4). The reason for such restraint in the accomplishment of miracles is, clearly from the passages above, the issue of faith (specifically, the lack thereof). Jesus' miracles were to serve the dual purpose of demonstrating both His Messiahship and the veracity of His message and claims. Therefore they were generally done on behalf of those who were willing to trust in what He said, and to trust in Him. So where He was met with a wall of stubborn unbelief, miracles were both pointless and inappropriate. Now faith is not an absolute commodity in the way that we imperfect human beings often exercise it (would that it were and we always employed it to the full). Jesus several times rebukes His disciples for their oligopistia (ὀλιγοπιστία), their "little faith" (cf. Matt.17:20). Faith can grow, like a mustard seed, from something very small into something quite large (Matt.13:31; 17:20). Sometimes it is fickle and not solid, like the seed of faith which never takes root, or quickly dies off, or is choked by weeds (Matt.13:3-9; 13:18-23). Sometimes it is limited by fear (Jn.12:42). Sometimes it can apparently be genuine but then quickly turn from acceptance to rejection (cf. Jn.7:30 with Jn.7:48ff.). The majority of those who followed Jesus at one time or another (having some level of faith) eventually turned their backs on Him (i.e., chose to abandon that faith; cf. Jn.6:66).
The boy's father in this passage, Mark 9:24, was clearly "conflicted" - on the one hand, he had his doubts about Jesus and his disciples, but on the other hand, he had a pressing problem and wanted to, needed to believe they could and would solve it. He had seen the disciples' inability to cast out the demon while Jesus was on the mount of transfiguration, and, as Jesus tells them later, this failure was due to their own lack of faith, at least in part (Matt.17:20). So it is perhaps understandable that the father lets slip in his request to Jesus an element of the doubt he is experiencing: "if you are able". Now the centurion (Matt.15:28) and the Syro-Phoenecian woman (Matt.8:13), we recall, were commended for recognizing that our Lord was completely able, if only He were willing (Mk.7:24-30; 8:13). And on many, many occasions, Jesus tells the recipient of His miracles "your faith has saved you". This father of the possessed child was clearly not in that category of those other exceptional people who clearly and unreservedly committed to or were willing to commit themselves to Him with such complete faith.
On the occasion in question here, Jesus immediately makes the issue clear, namely, that faith in Him must be genuine to be effective: "this 'if you can' [of yours, that's the problem]; everything is possible for the one who believes" (verse 23). The father's answer - "I do believe! Help my unbelief!" - is a fairly clear example, it seems to me, of "commitment with mental reservation". This is a far cry from the centurion's "just say the word" (Matt.8:8)! We cannot say that there was no faith present in this father at all (he had come for help, after all, professes "I believe", and in his second qualification of doubt asks for "help"), but it is not the most heartening thing to read (and cannot have been the most heartening thing for our Lord to hear). It is very important that this event has been included in scripture, because it give us an example, a negative one, of the type of unnecessary self-torture that people put themselves through, even when they feel God's call (in matters great and small), when they refuse to give in to Him entirely and take what He says with complete trust, acting upon what He says in complete faith. A true faith, undivided, single-minded, zealous and not lukewarm, is a very powerful thing. But a little doubt can destroy everything (cf. Jas.1:5-8).
Jesus did heal the young man - but not because of any unreserved faith commitment on his father's part (the emotion we see in this verse is for his own son, not for God's Son). For it says in verse 25 that our Lord only did so "when/because He say that a crowd was gathering" (cf. Jn.11:41-42). The presence of so many third parties transformed the issue from one this individual's faith alone to the proof of our Lord's Messiahship, making it acceptable and right to heal the boy regardless of the father's inability to give himself completely to Christ (and in many instances, after all, Jesus healed all comers, a situation which unquestionably included many like this person who were not complete in their faith; e.g., Matt.8:16; 12:15; 14:14; 14:36; 15:30; 19:2; 21:14).
Now we cannot say one way or the other what happened to this man, whether he learned from this experience (and from the miracle he experienced in the case of his son), but we can certainly learn from his lack of faith, and make a personal commitment not to test our Lord in ways like this, choosing instead ever to demonstrate a strong and uncompromised faith that trusts in Him without any reservations.
You might also check out Peter lesson #24, "Faith Dynamics" for more on this subject. Also, I have now written more on this passage in another place (hope you find it helpful): Gospel Questions V: Help my unbelief!
On the question of versions, I rather do like the NIV (that is the "old" version of the NIV rather than the TNIV). The "New KJV", or RSV, or NASB would all be fine - I don't unreservedly recommend the KJV for new believers, since the language is somewhat difficult to comprehend until one gets used to it - nor "Good News" nor any of the "easy listening" contemporary English versions. These all do too much violence to the true meaning of the original languages in my view. I have reviews with comments on some of these versions in the "Read Your Bible" file (click the link). I think even more important than the version is that you get the person a good study version, one that will actually answer questions in a Bible-believing way. The two I can vouch for are Charles Ryrie's "study Bibles" (he has them for several versions), and my all-time favorite is "The NIV Study Bible" ed. K. Barker, done by Zondervan publishers. The notes, charts, and illustrations are almost always helpful, and the cross-references are the best I've seen. By the way, I admire your efforts in sharing the gospel with friends - to this we have been called (2Cor.5:20).
Please also see:
Gospel Questions V: Help my Unbelief, Respecting our Enemies, etc.
Moving Mountains: Matthew 21:21.
Bible Basics 4B: Soteriology.
Seeing with the Eyes of Faith (in Pet. #23).
Fighting the Good Fight of Faith.
Faith Means Trusting God.
Pruning our Faith.
Hope this helps,
Yours in Jesus Christ,