Sorry, but you can't and shouldn't
harass pressure them into this kind of decision. I tried the hard sell on my husband 17 years ago and he still wants nothing to do with the Orthodox Church. Besides, when a son or daughter does this, it has the same effect as, for example, when a kid is 12 and wants a new gaming system. He just keeps hammering and nagging away at them. Did it get him what he wanted or did they just tune him out? And if they did get it for the child, it was with resignation and giving in, not the joy of a parent who buys a special something for a child and enjoys their unexpected happiness.
Parents are also used to teenagers and young adults who are on-fire with a new passion, whether it's a social cause, a new hobby or a religious faith. They will listen to you much more if you remain quietly and sincerely committed to your new faith, answering their questions if they ask, welcoming them if they decide on their own to accompany you to church. You have to remember, they've held their particular religious beliefs a lot longer than you've even been on the planet, and they may realize that something this important isn't done on a whim.
Don't mean to be preachy - it's just I've spent many years developing my know-it-all mother attitude.