After Yeshua rose from the grave, he spent many days with the remaining eleven disciples, explaining the Scriptures that they still didn't understand and instructing them on how they were to conduct themselves in the world in his absence. Before he ascended to Heaven, he told them and by extension us,

Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.
Matthew 28:19-20 ESV

The highest calling of God's people is to worship and glorify him. The second highest is to tell the world about Yeshua and to "make disciples of all nations". This doesn't simply mean to convince people to believe in Yeshua. It means to teach them all that Yeshua taught his disciples, including all that was written in the Law, the Prophets, and the Writings, what we know today as the Old Testament. This doesn't mean that every single person needs to dedicate his life to being a Bible teacher, but it does mean that we are to study the Scriptures and teach them when we are called to do so.

Maybe you will only teach your children, but you also have friends, neighbors, and coworkers who might have questions. If they know you are a Christian--and I hope they do!--how will you answer if they ask why you believe this or that doctrine or why you follow this tradition and not that one? It is always appropriate to ask God for guidance in these situations and to listen to his prompting, but if you haven't bothered to learn what he has already told you, don't expect him to tell you anything new.

You don't know what the future holds. You might be an auto mechanic or barista or lawyer today, but God might have something else in store for you next year. You will never go wrong in being prepared to teach God's Word to others. He could call you to teach Sunday School or start a website, or he could call you to keep fixing transmissions and being a good neighbor and advisor to your customers. In either case, a better knowledge of the Scriptures will serve you well.