Excellent question: "Where in the Bible is it taught that all believers will be spiritually fruitful? Does this mean there is no room for failure in the Christian life?" Excellent answer: Of course we all experience some degree of failure, but ultimate failure--returning permanently to unbelief and wanton sin--is not possible for true Christians. Romans 8:29-30 guarantees that every believer will be ultimately conformed to the image of Christ. The Spirit of God indwells each believer (Rom. 8:9). We have been made completely new (2 Cor. 5:17). And we are being transformed into the image of Christ (2 Cor. 3:18). Each of those truths guarantees that we cannot experience ultimate failure. The inevitability of fruit-bearing is repeatedly emphasized in Scripture. The basic principle of creation, stated in Genesis 1:11, is that everything bears fruit of its own kind. Here are just a few verses that expressly underscore this truth: Proverbs 12:12--"The wicked desires the booty of evil men, but the root of the righteous yields fruit." Jeremiah 17:7-8--"Blessed is the man who trusts in the LORD and whose trust is the LORD. For he will be like a tree planted by the water, that extends its roots by a stream and will not fear when the heat comes; but its leaves will be green, and it will not be anxious in a year of drought nor cease to yield fruit." Matthew 3:10--"Every tree therefore that does not bear good fruit is cut down and thrown into the fire." Matthew 7:17-19--"Even so, every good tree bears good fruit; but the bad tree bears bad fruit. A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire." Matthew 12:33--"Either make the tree good, and its fruit good; or make the tree bad, and its fruit bad; for the tree is known by its fruit." Matthew 13:23--"And the one on whom seed was sown on the good soil, this is the man who hears the word and understands it; who indeed bears fruit, and brings forth, some a hundredfold, some sixty, and some thirty." Luke 6:43-44--"For there is no good tree which produces bad fruit; nor, on the other hand, a bad tree which produces good fruit. For each tree is known by its own fruit. For men do not gather figs from thorns, nor do they pick grapes from a briar bush." John 15:5--"I am the vine, you are the branches; he who abides in Me, and I in him, he bears much fruit; for apart from Me you can do nothing." Romans 7:4--"Therefore, my brethren, you also were made to die to the Law through the body of Christ, that you might be joined to another, to Him who was raised from the dead, that we might bear fruit for God." http://www.gty.org/Resources/Issues&Answers/2545 I see in this brief answer the doctrine perseverance.