|Don't be this guy.|
Too often we relegate one's "testimony" to that time when he or she first accepted Jesus as Lord and Savior. But is that where it stops? Does Jesus trap us in amber as soon as we're his, only to be released on the Last Day? Inasmuch as we can stand on God's promise of a future salvation, our testimony continues day by day, as we not only testify of God's power to deliver, but live out the work of God in our lives! We're set free for a purpose, and it's not to simply wallow in his grace. As the old saying goes "we've been saved, we're being saved, and we will be saved."
Below are four indispensable elements of becoming the kind of disciple that makes other disciples:
Ok, this one is obvious, but the first thing a new believer must do is submit to the leadership of the Holy Spirit. Spiritual growth may not happen at the same pace for every new Christian (nor do we always notice it, or can measure it), but God is faithful to keep his promises. If we come to Jesus he "will in no wise cast [us] out" (John 6:20).
Tell others about that growth
Yes, your walk must match your talk, but let's not negate talking entirely! It's one thing to live as a Christian and have a solid reputation that inspires many to give their lives to Jesus (see below). But think about the Ethiopian Eunuch who was reading Isaiah and was very much confused by it (Acts 8). If Philip had not said something the eunuch would have never been saved and had never been baptized on the road to Azotus. There's "a time to be silent and a time to speak."
So Philip ran to him, and heard him reading the prophet Isaiah, and said, "Do you understand what you are reading?" And [the eunuch] said, "How can I, unless someone guides me?" And he asked Philip to come up and sit with him. (vv. 30-31)Be an example of growth
In Acts 9:10-31 we see that Saul/Paul's immediate conversion was enough to raise eyebrows, but it was his rapid growth in the Holy Spirit that gave Ananias, Barnabas, and others to confidence to confirm Paul's message when he "Immediately preached the Christ in the synagogues, that [Jesus] is the Son of God" (9:20). Be the change you want to see in the world, and you'll find that you're not alone in your walk with Jesus! Your story will attract others who are walking that same path after our Savior.
Growth does not stop -- even if the Holy Spirit has filled your heart with perfect love and ironed out all your desire to sin. We must daily put aside the flesh and follow after Jesus. That goes for all of us, and as Paul wrote the saints at the ancient city of Colosse:
"... Since the day we heard it, do not cease to pray for you, and to ask that you may be filled with the knowledge of His will in all wisdom and spiritual understanding; that you may walk worthy of the Lord, fully pleasing Him, being fruitful in every good work and increasing in the knowledge of God; strengthened with all might, according to His glorious power, for all patience and longsuffering with joy; giving thanks to the Father who has qualified us to be partakers of the inheritance of the saints in the light. He has delivered us from the power of darkness and conveyed us into the kingdom of the Son of His love, in whom we have redemption through His blood, the forgiveness of sins." --Paul, Colossians 1:9-14.