If telling the truth is hard then maybe what you are saying isn’t the truth. The only time telling the truth is hard is when one has made lies their refuge, and under falsehood have hid themselves. (Isa 28:15)
So do the insults and the rejection of what you are telling them upset, anger or offend you.
Remember, it isn’t your word they are rejecting.
So, are you really trying to convince someone else the things you are saying are true or yourself?
If the Gospel is hid it is hid to them that are lost and as written in Proverbs 18:2, the lost has no delight in understanding, but that his heart may discover itself. It is the Spirit of truth that does the convincing.
However, learn when to answer and when not answer as written in Proverbs 26;
4 Answer not a fool according to his folly, lest thou also be like unto him.
5 Answer a fool according to his folly, lest he be wise in his own conceit.
And if hold true with what you received you might just find that the seed you sowed, is beginning to grow without ever turning to look back.
Remember, it isn’t your word they are rejecting.