Gospel Guidebook: Getting and Keeping It Right 
Faith Precedes Regeneration (Effectual Calling)
Effectual Calling
The concept of effectual calling is also known as irresistible grace. In the order of salvation ("ordo salutis" in Latin), it really spans several steps and encompasses God drawing an unconverted sinner to Christ, causing the sinner to believe the Gospel unto justification, regenerating the sinner as a child of God, sanctifying the child of God, and glorifying the child of God.
Justification Precedes Regeneration
Many Reformed theologians equate effectual calling and regeneration. As a result, it is often taught that regeneration precedes justification. This, of course, means that regeneration precedes faith in Christ. However, this creates a big problem. If regeneration precedes justification, it doesn't seem possible that God could justify ungodly people as ungodly people (Romans 4:5). If God regenerates a person before He justifies him, is He really justifying an ungodly person? It seems to me that He would be justifying a regenerated person who probably already has the workings of the Spirit of God in his heart and life. If someone is bearing Spirit-produced fruit, it seems inappropriate to say that the person is an ungodly person who does not work (again, see Romans 4:5). This would also mean that justification would really fall within the realm of sanctification, and this would effectually be Roman Catholic doctrine. In contrast, I believe that justification precedes regeneration and have written about it extensively. For more details, see my articles Justification Precedes Regeneration, Justification of the Ungodly Man as an Ungodly Man, Justification and the Gospel of John, and Quick Rebuttal of Andrew Fuller's 'Strictures on Sandemanianism."
Faith Precedes Regeneration
If justification precedes regeneration, then obviously, faith must also precede regeneration. And there are dozens of verses that teach this. In addition to the verses provided in my articles referenced above, I could also add many others, such as Mark 16:16; John 3:16, 36; 5:24; 6:47, 54, 57; 7:38-39; 11:25; 20:31; Acts 2:38; 16:31; Rom 1:16; 10:9-10; 1 Cor 1:21; Gal 3:13; 4:6; and Eph 1:13. All these verses show that faith precedes justification (see the articles), eternal life, reception of the Holy Spirit, and salvation. Despite this, there are Reformed theologians like R.C. Sproul who insist that regeneration precedes faith. The verses that proponents of this view use as proof texts are so scanty and ambiguous that I am honestly quite dumbfounded by this viewpoint. In particular, the main verses they appeal to are Titus 3:5-7, which I dealt with in length in my article Justification Precedes Regeneration, John 1:12-13, which is admittedly ambiguous, but most likely supports the exact opposite conclusion, namely that justification precedes regeneration as I argue in my article Justification and the Gospel of John, 1 John 5:1, which at most, but not necessarily, can suggest that faith and regeneration are contemporaneous (more on this below), and 1 Corinthians 2:14, which is also ambiguous and does not preclude faith preceding regeneration. So, in contrast to the many proof texts to the contrary, proponents of the view that regeneration precedes faith don't have a single text to rely upon.
1 John 5:1
I will now comment briefly on 1 John 5:1a because it is probably appealed to the most by people who say that regeneration precedes faith. A literal translation of the Greek reads, "Everyone who believes that Jesus is the Christ has been born of God." Allegedly, because the verb "born" is in the perfect tense, this is supposed to imply that the believer was regenerated before he believed. However, it should be immediately obvious that the verse says nothing at all about a person in a state of unbelief. It only says what is true of a person who believes. This is their strongest proof text, but it cannot be logically deduced that regeneration precedes faith. It just isn't possible. In fact, in the very same context, John also says that the person who doesn't believe has made God a liar and does not have the Son (1 John 5:10-12). In the Gospel of John, we learn that a person who hasn't believed is condemned and does not have life (John 3:18, 36). There is no verse in the Bible that speaks of unbelieving people as regenerated. That's a fact. At most, 1 John 5:1a could suggest that regeneration is contemporaneous with belief, but only if the belief that John is referring to is inceptive (or ingressive) belief. However, the context seems to suggest that John is not talking about inceptive belief. For example, all throughout the letter John has been speaking of the characteristics of saved people. He says that they don't sin (3:9; 5:18), they do righteousness (2:29), they love the brothers (4:7), they believe in Christ (5:1), and they overcome the world (5:4). So, given this context, it makes sense for John to say that people who are living life as believers have been born again. And the Greek language supports this interpretation. The phrase "everyone who believes...has been born of God" is a generic truth statement about a participle that is acting in the capacity of a noun. The phrase "everyone who believes" can very naturally be interpreted as "every believer." (See my article Independent Adjectival Participles (Substantives) and Verbal Aspect for my details, although it is technical and requires a basic understanding of Greek.) John wants his readers to know that believers have been born again. And this interpretation is strengthened by 1 John 5:13 when he says, "These things I have written to you who believe in the name of the Son of God, in order that you may know that you have eternal life." John wants the believers to know that they have eternal life. In other words, he wants to assure believers that they indeed have been regenerated. This is a very natural interpretation, and it does not support the viewpoint that regeneration precedes faith.
Faith is a Gift from God
Faith precedes regeneration, but that doesn't mean that faith isn't a gift from God. The Spirit works faith in a sinner so that he believes unto justification and is subsequently regenerated. This is all part of the process of effectual calling. The common texts that are used to show that faith is a gift from God are Ephesians 2:8-9, Philippians 1:29, and 2 Peter 2:1. Besides these verses, our own experience witnesses to our conscience that we only believed in Christ because God made us believe. There is no other reason why we believed, yet so many other don't believe. We aren't better than they. We aren't better at making decisions than they. There is no distinction between us and them. It was only because God conferred upon us the gift of belief that we believe. I know from my own experience that prior to conversion I had refused an opportunity to hear the Gospel because I thought religious people were strange, but within a year's time, I had been reading the Bible. Against my expectations, God started to work His irresistible grace in my life and after many years of pursuing self righteousness, He mercifully granted me belief in my Lord and Savior Jesus Christ, justified me, and regenerated me. Faith is truly a gift from God.