Q: Growing up I was always told that if you sin after accepting Jesus you will lose your salvation. Is that true?
So basically you were taught that Jesus saves us, but staying saved is up to us! But the Bible teaches that our salvation is a gift from God and the forgiveness we are granted through Jesus is ongoing. — even when we sin.
One of the most wonderful promises from God's Word is found in 1 John 1:7 which says:
...if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus, his Son, purifies us from all sin.
The verb "purifies" is in the present tense in the Greek, which speaks of an on-going provision of forgiveness against present and future sins. It could literally be translated this way:
and the blood of Jesus, his Son, KEEPS ON CLEANSING US from all sin.
God knows that we are sinful and imperfect and He made a way for the sacrifice of His Son to keep pouring out His mercy on our lives.