Jesus commanded us to "make disciples of all the nations" (Matthew 28:19). But what does that mean? It means that to the best of our ability, being led by the Holy Spirit, we are to invite people to follow Christ. Then we are to help them get on their feet spiritually and help them to start growing and keep moving forward. We want to help them grow up.
Somewhere along the line, however, we have separated evangelism from discipleship. But we see no such distinction in Scripture The idea is not just to lead people to Christ and then say, "God bless you. See you later." Rather, it is to help them grow and mature in their faith. New believers need help as they make that commitment to follow the Lord.
New believers are just like new babies, and babies need help. And not only do new believers need help, but they need protection as well. The apostle Paul, writing to new believers in Galatia, said, "Oh, my dear children! I feel as if I'm going through labor pains for you again, and they will continue until Christ is fully developed in your lives" (Galatians 4:19).
You can't just turn a baby loose in a house. You have to watch them, because they get themselves into mischief all the time. You have to watch over babies constantly, because they are constantly getting into trouble.
The same is true of new believers. They make a commitment to Christ and are so vulnerable. Old friends will call up and ask them to engage in things they shouldn't. Old boyfriends or girlfriends will contact them again. Those temptations will come. And you, as an older, more mature believer, need to help them and guide them in that regard so they don't fall away.