No, it’s not possible to be a “semi-Christian” or “part-time Christian” (as you term it), because once you truly come to Christ, God adopts you into His family, and you are His child forever.

Think of it this way. When you were born, you became part of a family—and nothing can ever change that. Even after you grow up and leave home and establish your own family, you still are part of that original family. And even if you become alienated from your family for some reason and never want anything more to do with them, you’ll still be part of that family.

In a far greater way, that is what happens to us when we commit our lives to Christ. We are born again, the Bible says—and one of the consequences is that we are now God’s children and become part of His family. Even if we turn our backs on God, He doesn’t turn His back on us. The Bible says, “So in Christ Jesus you are all children of God through faith” (Galatians 3:26).

Make certain of your commitment to Jesus Christ. Then when temptations come, remember how much He loves you, and what it cost Him to make your salvation possible. In addition, make it your goal to grow stronger in your faith every day. Remember: A weak Christian is a vulnerable Christian. The Bible says, “Resist the devil, and he will flee from you. Come near to God and he will come near to you” (James 4:7-8).