Signs and wonders in the early church were performed by God through the apostles in order to establish and authenticate their authority. As Paul passes the torch to Timothy and he and the apostles write the epistles to instruct the next generation of the church, we find no emphasis and very little mention even of signs and wonders. Yet within Pentacostal and Charasmatic churches today, miracles, signs and wonders are promoted to the point that they even replace the preaching of the Word as a means of evangelism.
In Scripture, signs accompany and authenticate the historical redemptive acts of God in both the New Testament and well as the Old Testament; God indeed can and does do miracles today - we must not limit His sovereign right and power to do so; however, signs and wonders are not to be considered normative in the post-apostolic church after the first century.
Only the Gospel preached is able and sufficient to the saving of one's soul.