I can still remember the first time I rode a bike without training wheels. At first, it was frightening - I had to trust that, as long as I kept pedalling, the bike would stay upright. I had seen others do it, but it still seemed like such an impossible feat. But once I got going, I never looked back. Riding a bike suddenly become not only fun, but also useful - I could actually get places!
I think that our Christian faith sometimes works like that. Take the Old Testament Law, for example. In Galatians 3:24-25, Paul tells us that "the Law was our guardian until Christ came, in order that we might be justified by faith. But now that faith has come, we are no longer under a guardian...". The Law, in other words, acted as set of training wheels. Its purpose was to 'train' us in proper conduct ('guardian' is alternately translated 'teacher' or 'tutor') and to make us respect the actual laws that govern the universe (gravity/God). When God Himself came to show us how to live, it became redundant.
In fact, as Paul elaborates in several letters, it became a hindrance (e.g. Romans 7). Clinging to the Law when we already have Christ would be like insisting on using training wheels even after you've learned how to ride without them - you would be unnecessarily constrained. Paul therefore exhorts his readers to cast off the shackles of the Law and live in the freedom of Christ. As for Gentile believers, who bypassed the Law and went straight into free-style, the apostles gave them a condensed version of Law just to make sure they didn't hurt themselves (Acts 15).
Taking the analogy further, training wheels only really work on flat, smooth ground. When you start to navigate uneven terrain, they may actually destabilise you, because they prevent you from adjusting the angle of your bike to align with the real force of gravity (i.e. God). When Jesus healed on the Sabbath, for example, He was actually staying more 'upright' than the Pharisees who accused him of breaking the Law (e.g. Matthew 12; Mark 3; Luke 6, 13-14; John 9). Rather than obsessing with the letter of the Law, He lived by its spirit - which he helpfully spells out for us in Matthew 7:12/22:40 - and thus obeyed its real lesson.
Unfortunately, the kind of inhibiting, destabilising legalism exhibited by the Pharisees persists in modern Christianity. For example, I've written elsewhere about a simplistic, Sunday-School formula of salvation, whereby Christians go to Heaven when they die, leaving the Earth behind to live forever. While this may be a handy way of capturing some important truths, and is therefore useful for teaching children or new believers, the truth is actually that Heaven comes to Earth. If we refuse to discard the training-wheel doctrine, we therefore deprive ourselves of living in new dimensions of faith, in which the Kingdom of Heaven can be here and now (Matthew 6:9-13; Luke 17:21). What is more, we may be inclined to treat the Earth with neglect or even contempt, thus acting, like the Pharisees, in a way that is completely antithetical to the Gospel.
To be clear, I am emphatically not suggesting that we disregard the Bible or question its core doctrines, which are as indispensable as the bicycle's frame. However, we should always be digging deeper, moving from "milk" to "meat" (Hebrews 5:11-6:3; 1 Corinthians 3:2). Paradoxically, it takes faith to reconsider one's faith - but if we don't, we'll be stuck with a set of rusty, squeaky old training wheels.
