Is it a contradiction that Jesus said to keep the commandments but we're told we're under grace?
No, it is not a contradiction but a change of program. The command to keep the commandments applied to the Jew under the Law, while the present message is to believe the Gospel. Scripture is still God's Word, but not every portion was written directly to us. This is a change in God's modus operandi.
Les explains that the apparent conflict arose because the rich young ruler asked Jesus what he must do for eternal life, and Jesus answered, keep the commandments. But that was Law instruction for the Jew under the Law. Les says the caller's confusion came from mixing that sermon with the truth that we are not under Law but under grace. His answer was that it is not a contradiction; it is a change of program. Jesus today would not write to us to keep the commandments, because the present message is to believe the Gospel. Les calls this a change in God's modus operandi, not a contradiction.