What do you do with those who in your evangelism efforts profess to believe the gospel?
Mark Dever in his The Gospel & Personal Evangelism (a pretty helpful little book) rightly suggests that we should first incorporate them into the body life of a local assembly:
What do you do with those people who accept the news you’ve given and profess repentance and faith? No one book can fully answer this question. Certainly not this one. The Bible, however, gives us all the instructions we need. And we find there that these new Christians are to be brought into the fellowship of the local church. They’re to be given all the family privileges and all the family responsibilities. They’re to be baptized and admitted to the Lord’s Table. They are to be provided with guidance and counsel, love and support, care and teaching. Their relationship with the local church will mature and change just like their relationships with their spouse or friends. Sometimes one thing is needed; at another stage of life other kinds of support, correction, or instruction will be needed.
Throughout it all, the new Christian should continue be taught what it means to follow Jesus. From sitting under the preaching of the Word, to being baptized and taking the Lord’s Supper, to praying and studying the Word, to repenting and believing, evangelism should find its fulfillment in discipleship. The good news is not merely about the commuting of an eternal sentence but about the commencing of an eternal relationship. Truly trusting Christ will always show itself by following him.