I will believe it when the block size will be increased. Not before. I have absolutely no reasons to trust them.
Believe what? Their code is already out in the open. Are you even aware that the last functioning proposal for a Lightning network implementation was created by someone outside of Blockstream? No one's asking you to trust them.
I do not trust them to increase the block size, that is why it should be implemented by an alternative client. Unless the Core devs increase the blocksize, I will not trust them to do it. Especially since this has become a fundamental ideological disagreement, since not increasing the block size at all would lead to a very different future for Bitcoin compared to the future that restricting the block size would lead to.