For some reason, I've had a hard time jumping into this discussion, but it's a good one--one very worth having. :)
I would tell these new believers to spend time reading and studying their Bibles everyday, and I would emphasize the importance of prayer. I would also tell them to be sure and have regular fellowship with mature Christians.
In addition to these things, I would teach them the importance of walking by the Spirit. This means living in submission and obedience to the guidance of the Spirit 24/7/365. This is one of the main things that sets Christianity apart from all of the religions of the world. As believers in Jesus Christ, we have God Himself indwelling us and guiding us through the Spirit, which is amazing! In Galatians, we see the benefits of walking by the Spirit by God's grace through faith in Him.
Galatian 5:16-25-- But I say, walk by the Spirit, and you will not carry out the desire of the flesh. For the flesh sets its desire against the Spirit, and the Spirit against the flesh; for these are in opposition to one another, so that you may not do the things that you please. But if you are led by the Spirit, you are not under the Law. Now the deeds of the flesh are evident, which are: immorality, impurity, sensuality, idolatry, sorcery, enmities, strife, jealousy, outbursts of anger, disputes, dissensions, factions, envying, drunkenness, carousing, and things like these, of which I forewarn you, just as I have forewarned you, that those who practice such things will not inherit the kingdom of God.
But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law. Now those who belong to Christ Jesus have crucified the flesh with its passions and desires. If we live by the Spirit, let us also walk by the Spirit. Let us not become boastful, challenging one another, envying one another.
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