Well, they may not reject the miracle but instead reject God. The scenario I see is Christ returning performing miracles supposing this wasn’t kept from the public by the media but made news. There would be a certain percentage who would reject Christ and God because of too many disagreements.
Again, the media and academics and scientific community would be the Pharisees. They would keep saying, “why God this, why God that, what if this…etc…”. Then like the Pharisees when they don’t like what they hear, it would be a mass movement to reject God. Again Atheists already do this with their hypotheticals.
As for what you can do to greater grow your Faith. Pray, pray the Rosary. Seek and ye shall find. Ask God not for an easier life but a tougher life to build your Faith. What I learned from Paul and Acts of the Apostles is God wants growth. Challenges, difficulties paying penance all lead to growth. God puts signs all around us.
You may get to a certain point when you know for certain there is a God. Then you grieve for the sinner, you become repentant over your own sins. Again a lot of work is involved and it takes time. Another problem for the secular community would be they would want everything easy, for that alone they would reject God and his miracles.