Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me.  I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing. - John 15:4-5
You can’t test-drive Christianity.
There is a deadly misunderstanding of the gospel that I often hear. The misunderstanding is that you can begin to live for God before you come to Christ. It is the idea that you can try out Christianity before you become a Christian. It is the idea that you can see if you would make it as a Christian before you go all the way.
Here are some things I have heard people say:
"I need to clean up my life before I come to Christ."
"I’m not ready to be good enough to be a Christian."
"I think I can handle this; I’ll try it out for a while."
For many in my experience, this Christianity test drive has meant trying to be a good person and doing what’s right: to not gossip, steal, swear, get angry, etc., and instead to read the Bible, come to church, and help serve somewhere. For others, it is mostly a thought experiment where someone tries to imagine themselves as a Christian.
In any case, it doesn’t work. It can’t work.
Christianity is not one of many religions you may take for a spin like a car from a dealership, free to return it if you don't like it. To become a Christian is to be born again, to be regenerated (literally, re-genesis-ed), to be brought to life from death. It is not a casual choice but an unrepeatable event, and it only happens by the power of God himself, not a simple choice on our part
We tend to think that the question is whether Christianity will meet my needs. We get it backward. The question is not whether Christianity meets my needs but whether I understand its demands.
To become a Christian is not a matter of our choice, but of God’s mercy. It is not whether we will decide to give God a try, but whether God will show us mercy.
Do you see the difference? God doesn’t need you. Christianity doesn’t need you. You need Christianity. The truth is not validated by your assent to it. God’s worth is not contingent on you. Your worth is contingent on God.
The problem is that we are too provincial in our thinking, restricting our perspective to our own personal experience, perhaps including the experience of a few others, and sometimes trying to consider from a global perspective. But all this is too small, too limited. God is transcendent, eternal, infinite. And earth is not the only place teeming with life and creation. The heavens are rife with angels fallen and holy, along with principalities, powers, rules, and the mighty hosts of heaven. We do well to consider how small we are, how un-subjected to us God is, and how subjected to him we are.
The question is not whether we will answer God’s call, but whether he will answer our cry for mercy.
This is where Christ comes in. How we need him! There is no market of religions, each offering their own unique benefits and just waiting for the right kind of driver. There is only one truth, one true religion, and one path to life.
Scripture says that he who knew no sin became sin for us that we might become the righteousness of God in him. This is the crucial exchange that took place on the cross and which we need to be applied to us. Christ’s righteousness must be credited to us and our sin to him so that we might be counted other than what we are.
Scripture also says that God makes alive with Christ those who were dead in transgressions and sins. You cannot live for God before you are made alive by God. Just think about the logic of it. It doesn’t work. You can’t live for God apart from Christ. A dead person can’t “try out” life.
The first step toward Christianity must go through Christ. So often we focus on the cross of Christ that we treat the tree as if it had all the power! The power is not in the cross but in the Christ who died on it. We do not have a tree to deal with, but the creator of trees who allowed himself to be killed as a man on that one.
The plea for life is prerequisite to living for God. We are told in Romans 10 to call upon the name of the Lord for salvation. This call places us front and center before Christ in all his current glory - not the cross, not the past, but Christ as he is now, seated at the right hand of the Father in heaven. And we cry to him for mercy.
So no, you can't test-drive Christianity because becoming a Christian does not fundamentally depend on you but God. The question of whether you will be a believer depends on God regenerating you. To become a Christian is not a simple choice but a divine act.
And guess what? Things really don't change much once you are a Christian. Apart from Christ we do nothing. As life starts, so it continues. This is why it is necessary to live for God through Christ.