Read Romans 10 in its entirety. When the Gospel (the Word of God) is preached the Holy Spirit convicts ad convinces sinners. And give heed to the words of Abraham:
LUKE 16
27 Then he [the Rich Man] said, I pray thee therefore, father, that thou wouldest send him to my father's house:
28 For I have five brethren; that he may testify unto them, lest they also come into this place of torment.
29 Abraham saith unto him, They have Moses and the prophets; let them hear them.
30 And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent.
31 And he [Abraham] said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.
What was Abraham saying? If people will not hear the Gospel (which is also found in Moses and the Prophets) neither will they be convinced EVEN IF A MIRACLE SUCH AS THE RAISING OF THE DEAD were performed. Indirectly, he was referring to the resurrection of Christ.
Today God performs miracles daily for believers (and even unbelievers) all over the world because of His grace and mercy. But He has appointed the Gospel to become the power of God unto salvation for those who will believe (Rom 1:16).