Dear brothers and sisters in Christ,
When Jesus sends out the twelves, He gave them these instructions (among others):
"As you enter the house, greet it. And if the house is worthy, let your peace come upon it, but if it is not worthy, let your peace return to you. And if anyone will not receive you or listen to your words, shake off the dust from your feet when you leave that house or town" (Matthew 10:12-14).
When is the Gospel a burden?
When we believe that it is our task to prepare the heart of another. But Jesus didn't give that responsibility to those He sent out on His behalf.
Their task was simple: bear witness to the good news that they had received in Christ Jesus.
Nothing more. Nothing less.
And if anyone did not receive them, or their words, there were others who needed to hear that good news. "Shake the dust off from your feet" and go on to another.
There are many today who will not receive the Word, no matter how clearly it is communicated, no matter how convincing an argument is presented. But that is not your burden.
Carry out your priestly vocation and pray for him or her. Pray that the Word you have shared, sharper than any double-edged sword (Heb. 4:12), will settle in and at some point produce the fruit of repentance and faith.
But in the mean time, move on to another, for Christ desires all men to be saved (2 Tim. 2:3).
May it be according to His will. Amen.